That's basically meant for Mint 12... Although some info is still applicable, don't provide information for a new Mint version which was meant for an older Mint version.
You can also use synaptic to install programs. As long as you know the name of the program you want to install or what kind of application it is you can search for it in Synaptic. Basically, the Software manager is an easy-to-use and user-friendly GUI for synaptic.