go up to her after class, introduce yourself is she doesn't know you, and ask her if she wants to go to a movie or something sometime

i wouldn't recommend straight up saying you have a crush on her

well lil wayne i would do the same thing be bt u got a good point bt dis keisha u big fan of mind nice chattin with u

What you should do is get to know her (if you dont already) or just make it really really obvious