How To Use Live CD

["MikeA" <michael avila 1 sbcglobal net>]

Pardon my stupidity. I am new to Linux and to Gnome. I appreciate any help to understand how to use 
the CD so I can determine if I like Gnome.

I downloaded the .iso file and put it on a CD. I tried to boot from it but that would not work. So 
how do I read the CD from Linux? I have Centos 4.2 installed.

Thank you for your help.

Mike