Books about sexual knowledge are also mixed. Many books are written to sell money, and they all talk about sexual psychology or topics that are neither salty nor light.

If you want to learn, I recommend you to read the book Sexology Viewpoint.

You can have a look at the details of this book. After reading this book, you will have a general understanding of sex, your body and some diseases.

After that, you can watch some investigation reports, such as Kinsey, and some videos, such as bbc's "2 1 Century Girl's Sex Guide" (the name should be uncertain, you can call me if necessary).

After that, if you want to know what kind of body position is more comfortable and other practical things, you can watch American av and try it with the person you like, because people are different, and small gender differences may make a big difference.