You put the install disc of the OS into the computer and it will prompt you to hit any key to continue follow directions it will copy some files and so forth. Then it will restart your computer (DONT remove disc) and it will ask you to press any button again but don't do it this time.. Let it run and it will boot into another windows install GUI and start installing complete windows..
Once that is complete it will restart again and you should be able to boot into windows. Then you may remove the disc and install all your drivers.