How to install Add-On applications
Prerequisites: add universe and multiverse repositories.
You can install add-on applications easily, see: http://www.ubuntuguide.org/#add-onapplications
If you don't like the command-line, just use the GUI called Synaptic. It can be found under System -> Administration -> Synaptic Package Manager. Before use you should refresh the list of known packages.
If Synaptic isn't there, it can be easily installed with the command-line "sudo apt-get install synaptic".