Drop the Shadow in Photoshop

Drop Shadow is a tool you can select to place behind an image in Photoshop. I found this to be more difficult task when I tried to do it on my project. I had to select the layer and then select drop shadow. Holding the command key allows you to alter the shadow to making it either longer or shorter.

If you want to make the shadow more opaque you can select opacity. I think that this would be a helpful tool if you were trying to make two images combine with the same light source.