How do you format and install a nonbootable windows operating system?

I need a step to step guide to formating and installing a nonbootable windows 98 and windows xp or windows vista operating system .Do you really need a format disk to install these operating systems? and how do you replace your existing operating system with a new one . Where can you download this format disk ?How do you format and install a nonbootable windows operating system?
do a google search for win ** 'boot disc' or 'boot disk' that'll lead you where you need to go to find it.. and yes, if the install you disc you have is not a bootable copy, you do need a boot disc or format disc, and to replace an existing os, all you need to do is format the drive partition it's on... or if the os you're trying to install is newer than the one you have, all you need is the boot disc and the new os....and the new os disc will simply erase the old, format the partition, and begin installing itself for you.How do you format and install a nonbootable windows operating system?
if you have another windows, you can install the new windows as a ordinary software. I mean you should boot up your computer with old windows, put the Windows CD into the CD-Drive and click on the installation file. If you don't have another windows on your pc, you should use bootable floppy otherwise you can't install the windows from the non bootable CD.