You mentioned Red Hat and since some versions of Red Hat are no longer free to download... I stay away from it but this is a good place to start
Fedora is a Red Hat OS
Go there and choose the one you want but to download it you need a computer with:
1. cd/dvd burner
2. Nero, Alcohol 120 or some burning software that can handle the image type (likely ISO)
3. Blank CD or DVD depending on the image downloaded.
Downloading an OS is slow. Your internet connection may usually be fast but maybe the Linux site is not....
I have gotten free Linux distributions from books about Linux, College campuses and from friends that use Linux as it is not illegal to install on more than one computer. I hate downloading Linux but have when I had to.
Once you have the 'disc image' (that is the file that says x86_blah_blah.iso) you need to open the software that you will use to burn the image to a disc and find the part that says 'burn from image' and then locate the .iso image through the computers interface and start burning it... the end result, it will be bootable as Linux is not nearly as picky as XP, 2000 or the cursed Vista. SO>>>>
once the cd spits out and says burn successful or makes whatever sound that means it is done, you can insert into the computer needing the OS and simply hold the power button down for 10 seconds and then turn it back on.
(the 10 second thing is a hard reset and this is the only time that using it will not hurt your computer as if the file system is corrupt from it... you will be formating it to reinstall anyway.)