Why would new players want to join 5v5 games? Don't join 5v5s, they are bound to be too hard for you, and no-one has enough time to give you the advice you need. Even if the teams are 'balanced' rather than stacked, the odds are that you'll be right next to a player far better than you, who is in a hurry to stomp you on behalf of his team.
I don't see how that situation is much different from 1v1, 2v2, 3v3, or 4v4. If anything, a newer player might have more leeway in a game with 9 other experienced players (4 being on his team) because he won't have as large of a burden of having to win the game for his team as he would in a 1v1, 2v2, or 3v3. He might also get lucky and start in an eco slot. It's also easier to balance the teams the more players you have. It's also easier to migrate to the center of the map and to try to stay alive while the other 4 players on your team try to win the game, which they very well might do if one or two players on the other team aren't all that great, either. The effective loss of 20% of the team in a 5v5 isn't as crippling as the loss of 33% of the team in a 3v3 or 50% of the team in a 2v2. This means that a saavy new player in a 5v5 might actually be able to climb back into the game later or figure out some sort of a way to make a contribution to his team.
I've played one or two games and they were fun. I think one addition that would make online more fun for this game is being able to talk ONLY to one single player instead of just ALL or PARTY so I can backstab and double cross and set up secret trade alliances and agreements and such.
The command you are looking for, to privately chat with one person, is Whisper, /w "Name". You can press <TAB> repeatedly until you see the name you want to whisper to in game.
I can barely handle the computer on normal and most humans are like the comp on hard right?
It depends on players' experience. Very experienced players will probably feel more like Vicious AI. Brand new players will probably feel more like Hard AI. One huge difference is that you will feel that you are really playing a strategy game and not a game against a buffed up brute with the strategic thinking ability of a toaster.
It does sound to me like you need much more practice in single player before ever coming online. You have your games set to "Locked Teams", right, so that the AI doesn't gang up on you, making it 7 on 1 agaisnt you? People probably shouldn't try to play it online against human opponents until they can beat the Hard AI easily. Do note that you can always come online and play Comp Stomps with other people against AI opponents.