When you check the Graphics tab, you can see that no mesh has been generated yet. To generate the mesh for the named selections in the mesh worksheet, execute the following command:

mws.GenerateMesh()

When you execute this command, the steps are processed one by one in the order specified by the worksheet. For each step, the bodies identified by the named selection are meshed using the meshing controls applied to them. By watching the mesh generation in the Graphics tab, you can see the order in which each body is meshed.