Let me give you some advice.
First off, please don't act like a fool. Second, just walk up to her and start a conversation. Ask her what type of music she likes, what books she likes, etc.
It can take some time to ask your crush out. It can either take from 2 weeks, to even 2 years. Just be patient about it. For me, it only took 2 weeks.
If you are lucky enough, she might ask you for your number(that happened to me, also, that is a bonus), and might ask you out(BONUS+!).
EDIT: If she doesn't want to talk to you, maybe she isn't your piece of dinner. Not all girls are nice. They can be very pushy, like the Directioners in my high school! Girls can also use you for money, so beware, and keep an eye out.