Because sitting in front of a computer and installing with media is so 90s, I provide these two links. There are many other places that describe the same thing.

http://www.ioncannon.net/system-administration/99/upgrade-fc5-to-fc6-with-yum/
http://www.ioncannon.net/linux/68/upgrading-from-fc6-to-fedora7-with-yum/