adding photos to photos

Addition to hatstead's reply:

If you want to add the entire photo (B), select all of it (Select > All, or Ctrl+A). Then proceed with step 3.

Yes.

1. Open the photo that you wish to add something to (A)
2. Open the other photo (B). With B open, use one of the selection tools, e.g. lasso tool or selection brush, to select the object which you wish to add.
3. Go to Edit>copy to place it on the clipboard
4. Go back to A, then Edit>paste. The object B will come in on a new layer
5. Activate the move tool and position B, and resize with the corner handles of the bounding box.