How should i approach her and how should i talk to her?

[That guy]

I stopped talking to her for awhile because i got mad over something she did and i realized that i shouldn't have done it. We don't really know each other. So how should i approach her when i see her in my class again?. She sits with her friend. So should i sit beside her? Or should i wait until the class is done to talk to her. I need to talk to her privately. How should i approach her or what should be the right etiquette.