As an exercise, have a look at the picture to the right that represents the X-Y-Z \"right hand rule\" also called right hand coordinate system as it is used in X3D. \"x\" is your thumb, \"y\" the index finger, and \"z\" the middle finger. By simple rotation of your hand you can make it fit with the sketchup representation.
Both the free and the pro sketchup versions can be much enhanced with so-called plugins. To install a Plugin, copy its files directly to the sketchup plugins directory, e.g c:\\programs\\google\\google sketchup 8\\plugins. After restarting plugins you then will have additional tools. Usually there should be a new tool palette. 1e1e36bf2d