You have to boot from a DOS start up disk.
Go to your MB website and follow their instructions.
You can make a start up disk by inserting a floppy disk
in the drive, and in Windows explorer right click on the drive
(usually A) and check the format option then check the "Create an
MS dos startup disk". This will give you a boot disk.
<b>You get what you pay for...all advice here is free.</b>