Add a Layer
There are lots of ways to use layers to add two photos to a project, but let's begin with a simple method. I'll describe how the process works in Photoshop Elements, but the technique translates to many other photo editors as well.
To begin, open two photos in Photoshop Elements. You'll see them in the Project Bin at the bottom of the screen, but only one will be in the workspace at a time. Your first task is to copy the image in the workspace: Press Ctrl-A
to select the entire photo, and then press Ctrl-C
to copy it. Next, double-click the other photo in the Project Bin. That image should now appear in the workspace. In the menu, select Layer, New, Layer
and click OK
in the New Layer dialog box. You should see an empty, transparent layer on top of the photo in the Layer Palette. Press Ctrl-V
to paste the copied image into that layer. The workspace will show the new image, but fear not: The other photo is still there, underneath.