Go to http://www.rarlab.com/download.htm and download the file, or:
wget -c http://www.rarlab.com/rar/rarlinux-x64-3.8.0.tar.gz
and copy the file to /usr/src
# cp -dpR /home/esteban/Downloads/rarlinux-x64-5.2.1.tar.gz /usr/src
# cd /usr/src
# tar -xzf rarlinux-x64-5.2.1.tar.gz
# cd rar
# make
Output:
mkdir -p /usr/local/bin
mkdir -p /usr/local/lib
cp rar unrar /usr/local/bin
cp rarfiles.lst /etc
cp default.sfx /usr/local/lib

How to use rar:
$ unrar x filename.rar
Or use the program Archive Manager which is going to work now with the mouse, RIGHT CLICK and EXTRACT HERE...