No sweat, nita. Foramatting is quite simple to do.
First of all, make sure you saved anything you don't want to lose on to another disk if you have two fitted, or save to a collection of CDs if you have a CD writer.
This is just a case of saving files you have created yourself, plus any downloaded files you want to keep. Don't worry about Windows itself, or any of your programs, as long as you've got the Windows install CD, and the discs for your programs. You also need to check you have the driver-discs for your sound-card, graphics-card, modem etc.
With all that out of the way, you are ready to format the C: drive.
You will need a Windows 98 Startup Disk -- a floppy disk sometimes called a 'Boot Disk'. You should have made one of these with Windows -- they call it an 'Emergency Boot Disk'. If you didn't make one, and Windows is already 'broken' so you can't make one, you can download a free utility to make one from here: http://www.bootdisk.com
You will, of course, need a working PC to do that. On bootdisk.com, download the 'Windows 98SE OEM' boot disk.
When the startup disk has been made, put it into your PC and start it up.
Eventually you will get a white menu on a black screen.
Choose the option to 'Start Computer With CD-ROM Support'.
Eventually the screen will stop at the DOS prompt like this A:\>
Type FORMAT C:
You will get a warning about losing everything on drive C: Are you sure?
Press Y and [ENTER]
How long it takes depends on the size of your C: drive.
At the end it will say somthing like:
"Volume Label [ENTER for none]"
Just press [ENTER]
Formatting of C: drive is now done!
I assume you will now want to re-install Windows 98SE, so find the CD, stick it in the drive, give it time to spin-up.
With the keyboard, change the drive-letter from A: to the letter used by your cd-rom drive. If you only have one hard disk, this will usually be E:
You may think it should be 'D:', but the startup-disk uses that letter to create a temporary drive. Don't forget to type E: (with a semi-colon)
Now type SETUP and press [ENTER]
Hopefully Windows 98SE will begin to install.
Sorry to be so long-winded. Didn't want to miss anything out!