Haha! This is a toughy...but you'll get through it!
Ask her out somewhere...girls LOVE to be asked out. Go to the movies and dinner or something, real casual. Get to talking, ask her questions about herself (girls LOVE to talk about themselves!) and really listen. Then if you feel comfortable enough you can say "you know, I really like you!"
I'm a girl and I wimp out ALOT when it comes to guys I like. My friends ALWAYS tell me that the worst thing that can happen is the person doesn't like you the way you like them...and it's better that you know that so you aren't chasing the person with false hopes. Sometimes it hurts a little to find this out, but it's only temporary (Believe me, I know this well from experience!)
So go ahead and take your chances. Who knows? Maybe she feels the same about you! You'll never know if you don't say something though! I know I'm guilty of waiting for the guys to act...sometimes they just never do!