After you have the boot disk, insert it into the computer and restart.....When the very first screen appears (the BIOS version) press either F1, F2, delete, or ESC, it depends on which bios version you are using.......This will allow you to enter CMOS set up...Once you're in, locate the section that allows you to change the boot order of the drives....Generally, you will highlight the drive that you want to give priority with the cursor, and use the "+" or "-" keys to move the drive up or down the list.....It might be different with your BIOS
Your drive boot order should look like this:
diskette (floppy drive)
Cd drive
Hard drive
other (any other bootable drive)
Once you have made the boot order look like that, press F10 to exit CMOS, saving your settings......It might not be F10, it might be another key, but make sure you save the settings... Once you exit, your computer will automatically boot from the floppy disk that you inserted... Select the option: "Start with CD rom Support"
Let it load everything and when you come to the prompt, type: format c: press enter and let it format the hard drive..
Once it is done, the next thing you need to type at the prompt will be: setup.exe
Windows will then perform a scan of your hard drive checking it for errors and when it is done, hit "exit", and it will automatically go into the Windows 98 set up.......