When you restart the computer in MSDOS mode there only is one prompt.
My memory of Windows98 start menu options is a little blurry, but click the Start button, then click "Shutdown" then select the "Restart in MSDOS mode"
When the computer restarts, it should look the same as when you open a command prompt through windows (only it wont be inside a window, it will take up the entire screen.) then just type the command I posted in my last post and follow the instructions.
Good luck!