What a simple question!
There's a LOT involved with being proficient in sexuality with women (and much of it involves pure experience), so I'll try to keep this short and hit some of the high points.
Don't be nervous, that's the most important thing. Just remember that in all likelyhood, you're going to suck at it the first time. Most people do. With practice, you get better.
Don't watch porn to get an idea of what to do. A lot of what they do is either advanced or involves things that real women don't like all that much.
Remember that you're the man, and she will likely want you to direct her. If you want her to roll over, tell her...if you want her to get on her hands and knees, tell her.
A woman's skin is more sensitive than a man's, but the general rule I like to go by is that if I think that a certain touch will send shivers up my spine (in a good way), it probably will for her, too. When it comes to genitals, things are a bit different. Work your way from soft touches to hard touches, from rubbing outside to rubbing inside. Don't be too afraid to ask if she like something, but don't ask too much because it will make you come off as not confident which is a killer.
Probably your best friend will be research. Research the internet for what to do. Don't read sex stories...please! Read actual texts about sexuality and female erogenous zones (search Google for "female erogenous zones", go to the Kinsey Confidential website http://kinseyconfidential.org/). Remember, each woman is different, so a touch one finds mostly "meh", another will find mind-blowing. If one doesn't work, make your way to another one.
How long you last is different for each guy, but if you bust quickly, try to recover as quickly as possible to the point that you can go again. Most girls will be up for multiple times. If she knows you're a virgin, you're golden...it makes things a lot easier.
And always remember your condoms!