Running Bootcamp

Ok so I've done some reading up and I seem to be the only on in the world that can't get my bootcamp working on my mac.
When I run bootcamp assistant and try to 'Download the latest Windows support software from Apple' this appears: USB drive can not be used 'Please format the USB drive as single FAT partition.' Now I read I should "Open Disk Utility, select the USB drive in the list, click Erase tab, make sure Format is set to FAT, click Erase button." The only format options I see with "FAT" in it is MS-DOS (FAT) and ExFAT. I have no idea what to do at this point. (FYI: I'm using FreeAgent GoFlex Drive 500GB with about 240GB used by the back up I just completed.) Will going through all this get me passed this issue so I can download and install windows? I would greatly appreciate a step by step explanation. I've only been a Mac user for a little over a year and only realize now that I know nothing about them.
Everyone explains the Bootcamp setup as this simple process but it hasn't been that way on my end.

All advice will be greatly appreciated, Thank You.

Well vital info missing.

What 'puter? What operating system? Windows what version? And if your 'puter has an optical drive, or a second hard drive in that slot, Windows will only install from a dsic version.

For starters go into Utilities, open BootCamp Assistant, go into Help and see what this offers for whatever your machine and operating system may be.