Hello there, endorphin, and welcome to the boards, you'll find your in the right place for this sort of thing.
study study study.. a first time is always difficult, dont be surprised if there is a bit of blood, and a dose of crying after, losing your virginity is not easy on a woman. Just be as gentle as possible, and get it done right, and you'll be fine. The first time is more of a thing for guys, for women, in my experience, its what comes after the first time that is the best.
That said, if you really want to learn how to please her, check out
http://sexuality.org/ - it is an amazing resource of readings on how to get things right, from finding the right hole to finer techniques.
Oh yeah, and this forum is a host of information too, but make sure you get your background reading done.
Repearing myself - the first time will be memorable, but it will probably not be the best night of her life. Just be gentle and understanding. Besides, women love that in a guy
good luck