What should i do ????????

I'm 16.There's this girl i like in cl she's the smartest girl in cl.A few days ago she was sitting in front of me with one of her girlfriends.Before the cl started they started to take their books out of their bags and to slam them loudly on the table and then as a joke i did the same with my bag.In that moment she smiled a bit and tried to hit me one of her books.Also i sent her a friend request on facebook and she didn't accept or deni it for a week(i was sure she was online) and then she accepted it.also last year(we've been in the same cl for 3 years so i kinda know her and have her cell number) she kinda liked me but in the end it didn't work out between us and when i sent her a friend request on FB last year she denied it.Also to day we didn't study much during most of the cles and when one teacher was absent i was ping her in the corridor and she sed we did a lot of studying today(like a joke).Today i saw her looking at me and when i looked back she didn't look away.What does that mean and what should i do?