THIS IS A SIMPLE WALK-THROUGH for producing drop shadows by hand. In some cases you'll want to know and understand this process because you'll need a shadow that does not "drop" from the entire object, or one that you can manipulate as a separate object rather than part of the layer as in the Drop-Shadow layer effect.
This is an object, rastered on its own layer.
simple object
The first thing we'll do is duplicate that object to another new layer.
* Drag the layer to the "New Layer" icon at the bottom of the layers palette, or,
* Use the "Float" command: Command/J, or Control/J for Windows.