say "hey, i was wondering if you might want to hangout some time?" see what she says. if she sounds like she wants to, ask her for her number



oh and also, DONT FUCKING CHICKEN OUT OR YOU WILL FUCKING REGRET IT...lol seriousley though, you will

oh, and P.S
if she's got a boyfriend already, by all means become friends with her, but dont try and steal her away or anything. thats just fucking cold