Girls, what do you think about this?

This girl, I just talked stares at me regularly and so do I.... So, I went to talk to her yesterday in college campus, but she seemed uninterested and almost the whole time she was using facebook in her phone. So, I asked for her fb id. She said it was for some very "limited" friends so she wont give it to me. She seemed so uninterested that she even ignored me standing in front of her. After about 10-15 min she stood up(she was sitting) and asked me why I was asking her these ques. I felt like some1 slapped me in my face. But I was cool and asked if it is wrong to ask these ques. She did not said anything and left the campus leavving me as the last person in the campus. Believe me or not we were the only creature in the whole campus for the past two hours. Now, I am confused!!!!! We both, along with the whole class, know we have crush on each other. I just want some opinion about this. What should I do when I'm completely into her!!!!! Please help.

P. S. - She sometimes smiles at me when staring but I never smile. But unfortunately she is acting like nothing happened before.