I like this girl how do I talk to her?

[Ethan]

Okay so we are both freshmen in high school. She came from a different middle school. At first she din't notice me. After she rejected my friend, my other friend started talking to her (he dint like her) and that got us to talk for once. After that my ex, who is friends with the girl got us talking asking for a quarter. Next day i think she was looking at me but she looked away when i looked. She only does this in class but in the hallways, lunch, she doesn't do it. We had to do a presentation in a class we had. Her group was nervous and laughing. I smiled at her and it looked like she was laughing some more. And this one time she was with my friend (her and the girl i like are kinda close) i was walking to my next class and the teacher was late and the door was locked so the whole class waited outside. My friend was holding the girl i like by the wrist and she started walking towards me but the girl i like pulled back and they both stayed where they were. Does she like me? I like her and i wanna talk to her but im too freakin shy! How should i approach her?