How many times have you been out together and does a few dates make her your girlfriend? As Judy says you have to talk to her for a while and have fun, anything will do, school, friends, favorite places.
Am I wrong for thinking because she asked you out then you get right to the physical stuff like kissing? Have you even talked of going on a real date, or being a couple, or did you assume that's what asking you out meant.
No girl likes to be kissed by a guy who doesn't talk to her guy, or have good clean fun. That's why everybody tells you to talk to her, as you would a friend. You need a written script for that? I highly suggest you forget the kissing until you learn to talk to a person.