Remove RedHat, Install Windows 98

My mother bought a computer at the local Goodwill and it was loaded with Linux RedHat. She wants me to teach her how to use her computer, but I don’t know anything about Linux. I want to uninstall Linux and install Windows 98. Can anyone tell me (in plain english) how to go about doing this. I know the application side of computers, but I don’t know the first thing about modifying an operating system. Please Help!!!!