The clitoris is at the top of the front of her vaginal opening.
Here ((*))
You don't simply run your fingers inside he vaginal canal (although some women like this as well), you gently (or firmly, if she asks) massage this area, but as mentioned, only after some foreplay...this is a sensitive area, especially when it isn't properly lubricated. Follow her lead, ask her to guide your hand if she's comfortable with that.
I feel weird giving this advice to someone your age, but I lost my virginity at 15, so what do I know.
