If you know the type of hardrive you have, eg, manufactorer. You can input the cylinders, heads, sect..etc.......However, there is a utility called IDEID which you should be able to download off the net. You copy this file to a floppy disk...Boot the system, and run the IDEID file. This should find the correct settings of your hard drive. Take a note of them. Then, in the BIOS, go through the type numbers and select user, or something similar. Then, you should be able to enter the cylinders - head- etc..
When you boot with the floppy, and you have chosen cdrom support, make sure your windows 98 cd is in the cdrom drive.
type D: at the A: prompt and press enter/return. Where D is the cdrom drive, but it could be any other letter. Replace as needed
Once on D.....type
cd\win98
then type FDISK and press enter.
you should see 4 options. read each one. But the one you need is create primary partition.
Once you have created the parttion, you then need to format the hard drive.
Reboot as a bove.
Then type
format c:/u
where C: is the hard drive, and the switch u = uncondtional.
Then, having logged on to your cdrom drive, type
setup
and press enter.
This should start the windows 98 installation.
If you cannot get your cdrom drive to read the cd, clean the cd, and or the cdrom drive itself.