Walk up to her and say “hi.” Then ask if she’d like to hang out some time. If she says yes, make a suggestion (such as going to a movie). Have a second suggestion ready just in case she doesn’t seem keen on the first one. Maybe there’s a musical performance the two of you could go to (a local band, an open mic night, whatever). If one of those two options sounds good, set a time and place to meet (you might want to figure out in advance how you can get the two of you wherever you’ll need to go). Exchange phone numbers just in case something comes up (offer yours first). If you say something awkward, laugh it off and be honest: “Sorry, I’m trying to act like I’m not nervous and failing. Let me try again.” If she is interested in you, she’ll be nervous too—and likely to forgive you for messing up a little as long as you don’t get bent out of shape over it.