Awhh, Kastilla... You seem like such a lovely person, there's no need to be shy. c:>
It's perfectly alright to ask about this here, by the way. And to be honest, I understand the RP-shyness issue, and just shyness in general, both in real life and in-game.
The whole key is always, always, be yourself. :)
I already see some of your wonderful individuality in your posts, what with your awesome signature and the lovely text color you use in your posts~
While you have a point, that it is the internet, and there are going to be some rude people, there are also some very kind, welcoming people as well. It's those good-natured ones that you have to focus on, and never let the rude ones get to you. (They're gonna do what they're gonna do- but only you can control yourself. If you don't give them the time of day to bother you, they won't mean a thing.)
As for joining a roleplay, remember that pretty much everyone who runs their own roleplay is always happy to welcome new member. :) Even though they might seem a bit busy at times (say, if you're joining one in Fluorite), they still care about their members. And so long as you just roleplay, smile, be aware of the others in the RP, and be yourself, there's no reason you should be kicked out of it. In fact, once you get into it, you're bound to make some very close friends from joining these.
You seem like a lovely person, so don't let shyness get to you. ^-^ It takes time, but the more you try to be the first person to step out and say hello, you'll very soon find yourself coming out and feeling much more comfortable around new people. And this is both in-game, and also in real life. c:
I hope this was a little bit of help for you, anyway (xD), and I hope to see you around in-game, dearie. c: Maybe we can join a roleplay or something together. :D -nuzzle-