Press X to date?
Meh, just ask her. Tell her you like her, and that you'd like to know more about her. Ask her to a movie, or out for a milkshake, or whatever teens do these days. If she says yes, she likes you. If not, oh well, move on.
Opposed to what the poster above me suggests, don't hug her, especially if she's not interested. That's an easy way to get slapped down or accused of something inappropriate. I do agree about the smiling, tho i'd not go overboard with the big used-carsalesman grin.
If ya do get a date, congrats. Don't talk about yourself too much (you're better off asking her questions about whatever story she's just regaled you with), gaming is a topic you're better off avoiding unless she brings it up, or asks what your hobbies are, and finally DON'T STARE AT HER TITS.