My initial thought:Why is he telling us?! We're not the ones who need to hear it! And after further thought, I'm going to stand by that thought. It seems like you really like her as a person. And she is at least fond of you as well. But it can't go anywhere if you don't make it move forward by talking to her about it.
Do you have her phone number? That's a great way to start off. Simply start talking to her one on one. It will show her that you're interested in getting to know more about her. It also gives you the chance to really explore the feelings you have for her. I mean, you've interacted with her and know her somewhat. But talking one on one will give you the chance to get to know more. Then you'll really be sure about your feelings, you know?
Then just ask her to hang out one on one and catch a movie. I think she'll know what you mean. See how it goes. Just take this one step at a time and don't feel the need to rush. Of course, you are risking rejection. I won't lie and say it's a sure thing. There's a chance she may not feel the same. But you guys are friends and you should be able to stay that way even if she decides to not take you up on the offer of a date. Just make sure you're mature and treat her with respect.
Sorry I couldn't help more. But really the only advice to give is that nothing here will happen unless you make it happen. So take that risk and hope it pays off!
Let us know how it goes too. :)
-------
kid, I wrote back,
all lovers betray.