@mandophon,
Ask her out. Go have fun. Go to the movies. Rollerblade down the river.
Split a dinner at some diner. Fly a kite.
At some point the prom is going to come up, (it's in May or June, right?)
You should tell her that it's cool that she's going with the other guy because you two are going to have 100s of other nights.
Then kiss her really nicely.
Joe(have the best time of your life every time you can)Nation