If you have a picture of Elvis, and you want to make Elvis twins, just drag the name of the layer onto the New-Layer icon at the bottom of the Layers palette. This icon has two purposes: It will duplicate a layer if you drag one on top of it, or it will create a new empty layer if you just click it. You can also hold Option (Mac) or Alt (Windows) when dragging a layer up or down within the layers stack, or type Command-J (Mac) or Ctrl-J (Windows) to duplicate the currently active layer. Just make sure you don’t have a selection active; otherwise, this command will copy only the area that is selected instead of the whole layer.
Deleting Layers
If you’ve created a document that looks a little cluttered, you can delete a layer by dragging its name onto the Trash icon at the bottom of the Layers palette. Or, if you have a long distance to drag to get your layer in the trash, try Option-clicking (Mac) or Alt-clicking (Windows) the Trash icon instead (the Option or Alt key prevents a warning dialog box from appearing). However, this icon does not work like the trash on a Mac or the recycle bin in Windows. Once you put something in it, you can’t get it back (that is, without resorting to the History palette).
Transforming Layers
To rotate, scale, or distort the active layers, choose one of the options in the Edit > Transform menu; then pull the handles to distort the image. When you like the way your image looks, press the Enter key to commit to the change (press Esc to abort). If you want to know more about the transformation controls.