internalized screaming because i'm clueless about everything
Another introvert here. My suggestion is you learn to revel in the anonymity here. In all the game forums, you are known by your character's name. Only the GMs know your out-of-game handle, unless you wish to share it. So even if you goof-up in one game, you can join another, and no one else will ever know. :)
(Unless, of course, you always use the same character, with the same name, in every game... that's kinda a giveaway that it's the same player -- but it still doesn't reveal your out-of-game handle!)
No one but the individual GMs will know if you apply for a game, or which games, or how many. That's a heck of a lot of privacy with which to operate.
Helps me, at least. Trying to approach a group of gamers in person is beyond me; last time I thought seriously about Just Doing It, I triggered some kind of panic attack that locked up my lungs so I couldn't breathe. I was standing there in the game store thinking, "Oh, crap, I'm going to pass out from lack of air -- and won't that draw all kinds of attention!" Needless to say, I instantly abandoned the idea, which seemed to ease the panic, and once I could breathe again, I quietly departed. Not going to try that again anytime soon! :P
That's when I went looking online for games. I'm about 75% less shy hidden behind a computer screen. And I do have a considerable amount of confidence in my skills with the written word, which helps a lot.
So go look around, read a lot, and when you're ready, remember that no one can see behind your handle, and in a game, no one but one other person can see even that much. ;)