Originally Posted by
FrankMi
Masking is easier than you might think. In Elements you can use Adjustment Layers to create a mask. A mask is simply a hole in the upper layer so that you can see what is on the lower layer. Holes are black and reveal what is below. Anything in the mask that is white shows what is on the upper layer. Just like cutting a hole in a photograph to see what is in the photo below.
One neat thing about masks is that anything that is between white and black (a shade of grey) blends the two images together where the mask is grey. Lighter grey shows more of the upper image and darker grey shows more of the lower image.