I think things are being complicated a little too much for you here. Maybe I don't get exactly what your problem is, but from what I gathered you just wanted to cast shadows. Try this.

1 Load a figure and background prop/scenery

2 create a distant light

3 select the distant light and click the "cast shadows" button to turn the shadows on.

4 Adjust the position of the light using x and y rotate

That should really be all that you have to do. You can adjust the settings further from there if you wish of course, add more lights, etc, but remember that in D|S every light is created with the "cast shadows" turned off, so you'll have to turn them on on whichever light(s) you want to cast a shadow and leave them off of the ones that are just adding extra light to the scene.