How to get to talk to my crush

Hi! :)

So there is this girl I like. She flirted with me in class at school. I'm a shy guy, so I got nervous (because the classroom was full of other students), and didn't show any emotions back. She gave up flirting after a few scenes like this. This was like 2-4 years ago. But about 1 year ago, she asked if she could borrow a pencil of me. With a few other students around, she asked me. I don't know much about her. And we haven't had a real conversation yet. So I wonder if she still is interested in me. I regret that I didn't show that I liked her too. The strange thing is that I wasn't in love with here before she started flirting with me. I don't know why I just got in love with her the moment she flirted with me.

So I want to talk to this girl. But the problem is that the only time we can talk is at school or on the internet. She is usually with her friends, and going up to here in the halls (almost the only place we meet since we are not in the same class) while she is by her friends and other students around, will just be awkward. I want to get to know this girl more. So how am I supposed to start out? And I feel like I want to talk to her face to face instead of on Facebook. And what are we supposed to talk about? Maybe I should show that I am interested in her before we talk? But I want to know if she is still interested in me before I make a move, how?

That got a little messy. Sorry for that:none:. Please comment if any of this was unclear.
Thanks!