Experience is the best way to learn your way around the forums. Browse all the forums, read the threads. Pick up on how the smilies are used, and just have fun.

As for who not to hang around, you have to learn from experience. I don't think you'll encounter too many jerks around here. One person in particular flamed me once over interracial marriges. So, a few bad apples who have issues are here too. If they flame you, ignore them. Best thing in the world to do. Or inform the mods, but that wont get you very far. You never know who you shouldn't bother with unless you go into the forums and have experience.

Don't be discouraged by the bad posters, there's load of decent people on the boards. Post, and have fun.