How do I talk to this girl..?!?!?

Alright, I was at class the other day and in walks this girl who's never been there before and she sees me and sits a seat away from me. I looked over at my friend and we were like hm she's pretty good looking. So then I was just doing my work and about 5 minutes later I looked over at her and right as I looked she looked back and we both instantly turned away and I just sort of laughed. Then throughout the class I saw her out of the corner of my eye looking at me... anyways I don't know why but I couldn't talk to her...(forgot to mention earlier but when I looked at her and saw her face I was like holy sh*t this girl is beautiful) I was sort of nervous for some reason(I never get nervous around girls!!) So what should I say to her next time I see her..? Like how should I open a convo?