Vectorworks Tip Retaining Wall

You can create a retaining wall on a site model by using a couple of site modifiers. They can be pads or contours. 

The important part is to make sure that you use a grade limits to control the extent of the site mode change. 

podcast 225 - Nudge

Nudge is where you move objects a small amount using the shift+arrow keys. it can be useful, but watch out if you need to measure the objects.