Like Debian Linux, Fedora Linux comes with standard free software repos as a default.
If you want non-free software or something a little exotic, you need to add the essential repos.
You want RPM Fusion.
RPM Fusion is a merger of Dribble, Freshrpms, and Livna repos.
RPM Fusion offers software that Fedora and Red Hat don't offer.
RPM Fusion Non-Free repo requires some packages from the free repo, so both need to be added.
In your browser click the following two links to run install scripts to add both repos to your Fedora system:
RPM Fusion free for Fedora 13, 14 and 15
RPM Fusion nonfree for Fedora 13, 14 and 15
When the script runs, press yes to the questions to allow the install. You may have to give root password at one point.
After the install scripts finish, in an Xterm or similar, as root user run:
This updates the repo database.
Now you can search and install exotic packages not available from Fedora.