It took me an hour or so to find out how to install which was a pain, so for anyone having trouble here is the code your need. Replace the wget with the latest version to install the most recent, up-to date version.
These instructions are for the CLI, terminal version so no GUI here.
# wget http://rarlab.com/rar/rarlinux-3.7.1.tar.gz
# tar xvzf rarlinux*
# cd rar
# make install