Firstly, you need to install SketchUp.
Click here to install the latest version (Mac / Windows). Remember to select SketchUp Make - Educational Use

Never used SketchUp? Some step-by-step tutorials and a good introduction to using the orbit tool.

SketchUp Tool Series Training Videos

Familiarise yourself with the tools

SketchUp Training Videos

Using Section Plane to work on the interior

A useful reference card for SketchUp shortcuts