One of the new techniques in Vectorworks 2011 is planar objects. These objects are easy to make and they can be used to change your presentation techniques. You can now add color and hatching into your 3D models.
Click on the Preferences button.
The face will highlight.
Then the enter key to confirm the planar object. You can click on several faces if you hold down the Shift key.
You can do this for all sides of the building and the roof.
I have covered this in detail in my Vectorworks Essentials Tutorial Manual available from Vectorworks.