1. BIOs (F2, DELETE, F8, or F10)
2. Change the boot up settings with your BIOs to stop booting up from the hard drive to instead boot up from the CD drive.
3. Once you restart you'll get a little message asking you to hit any key to boot to the disc just tap any old key.
4. You'll get a blue screen and it will load up some files at the bottom and say the setup at the top.
5. Wipe everything by just deleting everything there pushing L once there is only one left or you only had one and deleted it you'll just have a empty hard drive.
6. Format (the slow way don't choose fast) and install and there you go your newly reinstalled OS.
If you don't have a disc call the company you bought it from and order in one.