By net shape, I’m guessing you mean take a mesh and unwrap it so it lays flat.
Here’s what I do:
Split your window so you have the 3d window on one side and the UV face layout in the other. In the 3d window, in UV Face Select mode, press the A button so you select all the faces. Then press the U button to bring up the unwrap menu and selcte LSCM. You should get the UV coordinates showing up in the UV image window.
You will notice that things don’t quite look right in the UV image window. This is because your model does not have any seams to help LSCM determine how to flatten out your model. Go back to the 3d model and go into edit mode (TAB), then select an edge by higlighting 2 conected vertices and pressing CTL-E or go to the mesh->edges->mark seam off the menu.
Make seams along one side of the mesh just as you would cut the mesh to unwrap it as if it were made of paper. For instance on a cyclinder I would make a seam around the top and bottom and a seam down the side so that I get 2 circles and a rectangle when it unwraps and flattens out. Just make seams where you think they should go, then start all over again. leave edit mode and back into UV face select mode and press A to select all faces. Press U to bring up the unwrap menu and select LSCM.
On a more complex mesh, you don’t have to do everything all at once. When unwrapping a character, I usually do the chest and back together, the arms, the legs, and then the head. After I unwrap each one, I rotate and scale the UV coordiantes in the UV image window so that they all fit on my texture map. If you got more questions, let me know.