USB and ATMega8 ?

Hi, im thinking of making my own board like arduino, I looked at the schematics but the ones on the main page do not include USB, can anyone post a link to adding a USB to the ATMega8 ? I really want to make my own board so I can know how everything works. If you post a link it doesn't necessarily have to be to arduino, since arduino is so complex I just basically want to learn how to interface the ATMega8 with USB so I can make my own board, the size I want it to be.

Yes it does! Schematic in .jpg Eagle schematics