I think the first thing you need to work on is overcoming your shyness (heh pretty obviously). Just do it in small steps. As you keep practicing your socialization skills Im sure you'll feel more comfortable around girls (or people in general). Do things like say "hi" to random girls in the halls, give random girls compliments, have short conversations etc.
I've been in your position with the 'crush', and trust me, the best thing you can do is go for it. (Although if you don't really know her then dont just go up to her one day and say "I like you" - you have to start small). Start talking to her now. I know how it feels, you keep waiting for that 'perfect time' to talk to her, but honestly, in my experience, that time never comes. You just have to do it. When I say start off small, firstly, you should try making eye contact with her a few days every week, and then after about 2 weeks, start smiling at her. After you start smiling at her, just go up to her one day and say something like "Hey, I've seen you around here a lot... (and continue from that)"
