In my previous thread on this subject I allowed myself to get sidetracked.
I have, following Mark's instructions, removed the Virtual Box that came bundled with my Mint 13 (Cinnamon).
Also, following Gearhead's advice, have downloaded the Deb7 version of Virtual Box.
All I need now is to know how I install it. I do have the GDebi Package Installer 0.8.5build1. Where do I go from here?