The full version of kicad is intended to be installed in /usr/kicad.
download the full archive kicad-full-version-yyyy-mm-dd.tgz from
http://iut-tice.ujf-grenoble.fr/kicad/
This is the "official" stable version

goto /usr/local
untar the file (tar zxvf <path to find the downloaded file>/kicad-full-version-yyyy-mm-dd.tgz)
to launch kicad, run /usr/local/kicad/bin/kicad
You also can copy the file /usr/local/kicad/bin/kicad.desktop to your Desktop and use it to run kicad.

smaller files and snapshots can be downloaded from:
http://kicad.sourceforge.net/