For this post, I'll walk through the process of building up a shape from scratch and editing it using the ShapeSheet. The shape itself won't be too complex, but we'll cover a few of the interesting features of the ShapeSheet.
To get started, create a new blank drawing (File>New>New Drawing). If you are a US user, you'll have the option of creating it in US Units or Metric. For this example, I'll use metric units. Using the Rectangle Tool on the Drawing Toolbar (you can add the toolbar by going to View>Toolbars if you don't see it), create a simple rectangle like this:
Now, select the shape and click on the "Window>Show ShapeSheet" menu item. This opens up the ShapeSheet window for the shape we just created. Next, tile the two open windows (drawing and ShapeSheet) so that you can see both at the same time. This will let you see the effects of the actions you take in the ShapeSheet window on the drawing page.
Just to get the hand of working with the ShapeSheet, try a few things:
One other tip: if you expect to use the ShapeSheet a lot, run in developer mode. Among other things, this lets you get to the ShapeSheet by right clicking on a given shape. To use developer mode, go to Tools>Options>Advanced and check "Run in Developer Mode."