How do I install Windows 98se to a PC system that doesn't have a OS at all? It has a CD-ROM. Do I need a boot disk or something?

Yes a bootdisk is a "must have" to install windows 98. If you do not have one I suggest you go to www.bootdisk.com and grab one there.

Liz, when I got my laptop off of ebay, windows had been removed, but they left the cd-rom dirvers on there for me, so I just had
to pop in the win98 cd and run setup from dos. They will probably provide you with some
instructions and links for drivers you might need to get off of the internet.

There are many versions of 98se , oem , update , upgrade & so on .
Here is a step by step tutorial .
http://www.pcnineoneone.com/howto/clean1.html

And if you need it , Device Manager tutorials . John .
http://www.microsoft.com/TechNet/win98/Reskit/Part5/wrkc24.asp
http://pcsupport.about.com/compute/pcsupport/library/weekly/aa022100a.htm
http://support.microsoft.com/support/kb/articles/Q133/2/40.ASP
http://www.winplanet.com/winplanet/tutorials/492/1/

if you are really stuck, as in may be your only computer, see if you have any boot disks that have MSCDEX on it. thats the basic cd driver. MSCDEX /D:MSCDEX001 /L:D would be command to set driver mscdex001 make cdrom drive D. or something

Just go to setup and make ur first boot device as CDROM and second boot device as HDD0. (Iam assuming that u have an original win cd or a copied BOOTABLE cd, otherwise this method will not work). Then just pop ur cd in the cd drive and restart the pc nad installation will being automatically. let me know the results.