Transmission can be installed quite easily through the repositories, however it is not part of the default Red Hat repositories. First we will need to install the EPEL repository to our server:
You can find the lastest EPEL repositories here:
https://fedoraproject.org/wiki/EPEL
For simplicity sake you can always just following my guide with version as of time of this writing, as it will be updated when you do an upgrade anyways.
wget http://mirror.pnl.gov/epel/6/i386/epel-release-6-8.noarch.rpm
rpm -Uvh epel-release-6-8.noarch.rpm