1. The game is solo-able. It is easier for some ATs to solo. The game is designed as a team game. There are great advantages to players that team.
2. We go on missions. We don't "quest".
There are two "settings" that you will see in the mission window. One is related to the side of the mission (hero or villain. The other is difficulty.
Difficulty usually sets the level of enemies in a mission. Your starting setting is "heroic". The even diff effect spawn size, the odd effect the level of the enemies. If you have set yourself to "invincible", you might want to cut that back down to "heroic" or "rugged" for a while.
If you are in the AE your experience my change.
If you get far enough ahead in some mission arcs, you might run into a situation that is above the normal play level. See if you can do some other missions and then come back to the other mission once you have leveled up again.
Part of the game is based on having a fear of the enemy and then eventually over-coming them. Some players don't like that fact, but I suggest enjoying the thrill of learning to fear enemies and then the sense of accomplishment when you are able to defeat them.
I don't know what level you are, but since you said you were in Atlas, I'm thinking it is pretty low.
Another option is...
If you are over level 5, head to Kings Row and go to the detective contact. He will give you a police radio. It will appear at the top of the contact window. The Police Radio provides zone level content that is appropriate to that zone and to your characters level.
1. The game is soloable for the most part. There is very little you can't solo. Trial accounts have restrictions on them, which is why you couldn't team with your friend. You also won't get past level 14 on a trial.
2. If you talk to a 'Field Analyst' in CoH of 'Fateweaver' in CoV, you can change the difficulty of your missions. If you've done this, it would explain why things are so tough. You're probably best to leave it at the default for now.
Your beginning contact should introduce you to a new contact when you've done the missions for him/her. Check the 'Contacts' tab on your nav bar. If not, you can talk to a Detective in King's Row who gives you the police scanner, which gives repeatable missions, or David Wincott in the Hollows, if you're above level 5.
They ALL float down here. When you're down here with us, you'll float too!
@Starflier
1. Soloing and Teaming
This game is designed to allow soloing - theoretically everyone can solo. But of course some characters are better at it than others. All villains can solo quite well, though Brutes are easier to learn. On the hero side, Scrappers are the most solo-inclined.
While trial accounts cannot start teams, you can still join teams. I THINK another player can invite you both to a team, then quit, leaving the two of you teamed up. I'm not sure though; someone correct me if I'm wrong.
You could also ask if someone's willing to show you two around. Explain that you and your friend are on a trial, and would like to see how teams roll. Trial accounts can't speak in zone-wide broadcast, but you could still ask in local chat in crowded spots in Atlas - like near Ms. Liberty or in the Architect building.
2. Mission Difficulty and Contacts
The 'challenge level' thing you see in the upper right corner of your mission window is difficulty setting. Higher difficulty means a) more enemies, b) higher level enemies, or both.
Unless you changed something, you should be on Challenge Level 1: Heroic, and Challenge Level 1: Villainous. This only affects your indoor missions, similar to instanced dungeons in WoW. It has no bearing on the enemy spawns you can find outdoors. I take it you're running into red and purple enemies on the street - well, you will. You should also be able to find some even-cons if you look around.
Contacts in this game will introduce you to other contacts as you finish their missions. Ms. Liberty will never offer you missions - she is a trainer, not a contact.
If you are Level 5 and above, you can visit Kings Row and talk to a Detective. He will appear in your contacts window, under the Detectives tab. And also on your mini-map, like all contacts. He will give you a Police Radio. The Police Radio appears in your contact window. Clicking on it will give you access to randomly generated missions. After you do a few Radio missions, you must speak to the Detective (in person) for a Safeguard mission.
Completing the Safeguard mission will give you a temporary power, and after you return to the detective, he will introduce you to a new contact. This is an alternative way of earning contacts. The temp powers are also quite worth it - the first couple of Safeguards give you jetpacks, which is a very cool thing to have on a trial.
Please note - there are also some areas of the game that have special storylines tied to that geographic region. The first is the Hollows. At level 5 you can enter the Hollows (from Atlas Park) and talk to the first Hollows contact, David Wincott.
I'm obviously talking about the heroside game here. For villains, you'd want to speak to your Broker (in Port Oakes) for a Newspaper, and earn contacts through Mayhem missions. Pretty much the same idea, different flavour.
3. Game Manual and Info Websites
You can download a pdf of the Official City of Heroes Manual from the game website.
I also highly recommend the player-run wiki site, Paragonwiki.com
@Acyl
VIRTUE
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As for soloing, yeah, you can solo most of the game. Scrappers and Brutes are the easiest solo Archetypes, they're durable and good at dealing damage. Any Archetype can solo, mind you, they're just the easiest.
BackAlleyBrawler: I can't facepalm this post hard enough.
ShoNuff: If sophisticated = bro-mantically emo-tastic, then I'm going to keep to my Shonen loving simplicity dammit.
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Completing the Safeguard mission will give you a temporary power, and after you return to the detective, he will introduce you to a new contact. This is an alternative way of earning contacts. The temp powers are also quite worth it - the first couple of Safeguards give you jetpacks, which is a very cool thing to have on a trial.
[...]
I'm obviously talking about the heroside game here. For villains, you'd want to speak to your Broker (in Port Oakes) for a Newspaper, and earn contacts through Mayhem missions. Pretty much the same idea, different flavour.
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Note, villainside, mayhem missions are the main way to get contacts.
And whereas on a safeguard, you want to rush to the bank to KO the villain robbing it, on a mayhem, take your time, work your way over (in fact, mayhems have trigger points that send an ambush after you, which safeguards do not have) to the bank, destroying stuff as you go 
Orc&Pie No.53230 There is an orc, and somehow, he got a pie. And you are hungry.
www.repeat-offenders.net
Negaduck: I see you found the crumb. I knew you'd never notice the huge flag.
If you and your friend are both on trial accounts and want to team together the easiest way is to approach another player (preferably with at least one veteran badge), explain to them in local chat that you're friends on trial accounts who would like to team with each other and ask if they could invite you both to a team and then quit the team.
You can also approach other players near your level range and just ask if they could invite you and your friend to a team if you want to join a larger team.
There are some jerks out there, but most players are helpful and willing to assist new players.
Dr. Todt's theme.
i make stuff...
Also, there are generally some nice people in the help (/hc) channel and will help you folks team up.
Orc&Pie No.53230 There is an orc, and somehow, he got a pie. And you are hungry.
www.repeat-offenders.net
Negaduck: I see you found the crumb. I knew you'd never notice the huge flag.
[ QUOTE ]
Also, there are generally some nice people in the help (/hc) channel and will help you folks team up.
[/ QUOTE ]Oh yeah, forgot that trial accounts have access to that channel. 
Dr. Todt's theme.
i make stuff...
Yeah, be careful with that reputation thing. I didn't understand it the first time I was sent to a Field Analyst, and I thought, "Yeah, I'd much rather be known as 'The Invincible Gravimetric Man' than 'The Heroic Gravimetric Man.'"
Suddenly my missions were next to impossible, and I didn't put 2-and-2 together right away and almost gave up on the game. I either asked here or in-game and somebody explained I wasn't changing my title but my difficulty level!
(Sometimes, I wish there could be a Dev thumbs up button for quality posts, because you pretty much nailed it.) -- Ghost Falcon
Someone may have mentioned this already, but you and your friend can team if you are both on trial accounts. It will require the help of someone who is not on a trial account. You will need to have this person invite both you and your friend to a team and then they will have to quit the team. The game is very soloable, but is much more fun on teams.
What server are you playing on? Each server has its own unique strengths and weaknesses in different types of game play-for example, Virtue is the roleplay server, Freedom is a good server to PvP on, Protector has a little bit of everything. If you prefer certain aspects of gameplay over other aspects, you may want to tour around the server forums and see what kinds of events are listed and what kinds of issues are being discussed. It won't always help you gauge which server is best for you, but it can definitely help to familiarize you with the kinds of players on each server.
Welcome to the game, both you and your friend, and hope you decide to stay a long long long long time! 
City of Heroes taught me that when the world is burning, you don't just stand by and watch, you grab a fire extinguisher and do whatever you can to stop it-even if it's not much at all. Sign the petition to keep City of Heroes alive HERE.
@MissKyo, Leader of the Teamsters coalition on Protector
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Someone may have mentioned this already, but you and your friend can team if you are both on trial accounts. It will require the help of someone who is not on a trial account. You will need to have this person invite both you and your friend to a team and then they will have to quit the team.
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I didn't see the part about another trial being involved.'
The easiest way to get help getting the two trials on a team together is probably using the [Help] channel. I don't know how much info is given on the trials at this point, but use the /hc command to send a tell on the [Help] channel - like ::
/hc me and a friend of mine are on trials and we would like to team together. Can anyone help us?
That should probably do it. Many of us are still very friendly and helpful and are more than willing to help.
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the mission now says "Heroic =" and all the mobs are red and purple to her.
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Was this mission something like "hunt 10 Hellions" (outside) or was this something like "Arrest Bonebreaker" (an instanced mission )?
Outside, when you get into certain zones, it's tougher. If you look at your map of (for instance) Kings Row, you'll see yellow parts, orange parts and red parts.
In Kings (which goes from about level 6 to 10) your yellow parts will be 6-7 or so, orange 8-9 and red around 10-11.
Oh. if you took the train from Atlas (level 1-6) to Kings (level 5-10) you may notice guys on the street getting a lot tougher in a hurry.
If you've got a regular mission and all of a sudden the guys inside are red and purple, and you haven't set your difficulty higher... I don't know what would cause that.
Welcome !
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Thanks everyone for all the info!
Hello to all.
My friend has come along to try it out as well and we were both kinda bummed out that we couldn't team up.
Here is it day 3 of my trial and I have to say, I like it alot. I'm an avid WoW player and this has made me want to log off of WoW and come play!!
I have just a few questions and I've been perusing the boards and support forums and just haven't found it. Though it could've been staring me in the face and I missed it.
1. Is this game soloable? So far, I've gotten a character up to level 5 soloing. Doesn't help that I've spent most of my time in the character creation portion, but hey.
2. When questing, I noticed the missions have titles on the right hand side, like "villian challenge", now when I made a hero, I got her to Atlas Park and was following the quest chain, but the mission now says "Heroic =" and all the mobs are red and purple to her. Needless to say, it's baffled me. I've gone back to the contact and Ms. Liberty but neither have any other tasks.
Lastly, is there a website or link I can go to that has the game manuel online? Or am I overlooking that too?