One of your commands in model space is unfold. Just right click in the outside gray area and select customize. Click commands tab and scroll down to find all commands options. Then go through the list to find the unfold command. You may have to join your parts first.
Ryan - Unfold is only available with the DL1 add-on product. Despite the fact that it shows up in GSD, it is not available by default. (and most people don't have it)
Also, Unfold is only for surface unfolding. It is not a good tool for doing sheet metal developments.
