How do i spend more time with a girl?

me and a girl, are, just friends i want to be more than that we talk to each other very little, we have one class together and that's the only time we get a chance to talk and in the hallway we always pretend not to see each other when we walk past each other we rated each other we talk on fb every now and then but i want to talk to her more. how can i spend more time with her?