I don't see any groups at all,so how do I join one?
I think you can apply to them with some sort of button, or if everything else fails, you can send a PM to any of the group leaders (blueeyedgabulov0o, Shadowknight, Mars the Great, Dark Chibimon, etc) and ask for details.
User CP -> Group Memberships
user cp is at the top of the screen next to your name and group memberships are on left hand side in the middle
Heh thanks for the help guys, you could also add a PM to anyone of the one's Mars Listed. Its not too long of a process really and if you need help, just ask ^^.