1. You need a bootable Xp, Vista or 98 CD.
2. Slot the CD into the CD drive as soon as you turn the system on.
3. Enter the boot sequence in the bios setup *** depending on your computer brand, you can enter the bios setup by pressing F2 that's for Dell and Compact is F10.
4. Once you set the system to boot from CD follow instructions on the screen.