Press 1 on the NumPad to get the front view. Look at the upper-left corner of the 3D View to make sure that the 3D View is in the Ortho mode. Press 5 on the NumPad if it isn't in the Ortho mode.

Move the lamp to the major horizontal grid line above the cube.

Press 7 on the NumPad to get the top view.

Move the lamp up until it is just to the right of the cube and level it with the center of the cube, as shown in the following screenshot:

Press F12 to render the cube.

Observe how the cube looks.

Press the Esc button to close the render window.

With the lamp selected, press the Shift key and the D key together, to make a copy of the lamp.

Move the cursor. The new lamp moves while the original stays put. Move this lamp so that it is centered below the cube, as shown in the following screenshot:

Press F12 to render the cube.

Observe how the cube looks.

Press the Esc button...