duuuuuude get her fired up nice and slowly, even tease her to the point where she's begging you to fuck her.
WHat I mean is - try touching her EVERYWHERE but her pussy...working backwards: pussy, breasts, inner thighs - the pussy should be touched last, then it will be nicely engorged and drippng and she'll be easier to work with.
But yeah - then concentrate on her clit, and add your MIDDLE finger (to start off) in when she's ridiculously wet and try and work your way up the inner roof - hitting past the rough patch and finding a small smooth patch, which should swell up the more aroused she is.
Use your mouth! Much more forgiving on the pussy than fingers if you're a bit of a novice.
Also, ask her to touch herself in front of you, ask her to show YOU how she likes it, how she plays with herself - then you'll have a better understanding of how to get her off...and then you can do it quicker, or draw it out nice and long - just experiment, but get her to show you how she touches herself, and you'll learn infinitely quicker.
Then you can fuck her - I still haven't had a virgin, I always chickened out, I like more experienced girls, and I usually droop when a girl shows real pain...go for it!
Damn...I'm really horny now.