You're not alone. About 75% of all women don't have orgasms through intercourse. As for whether a guy knows what he's doing, there's two sides to that. Even a guy who usually satisfies the women he's with might not satisfy every one. That's not because there's something wrong with the woman, it's because everyone likes different things. Some like soft, gentle touching, some rougher toughing, some like it fast, some slow, etc. Sexual partners need to work together and communicate what feels good and what doesn't.

The best thing you can do is masturbate. You might want to get a book, but the important thing is to learn what you like. By masturbating, you're learning about your own body. If you don't know your own body, how can you expect someone else to know what you like and don't like? Masturbation is healthy, and it's normally the first way we learn about ourselves in terms of sexual pleasure.

Try to be patient, and don't worry if you don't reach orgasm the first few times. You're experimenting, and there's no expectations. If you do have an orgasm, fantastic!

Do it in front of a mirror, so you can see what you look like. Learn about your body so you can show your partner where and how you like to be touched. Have him show you the same thing about him.