Clipping masks are similar to layer masks in that they both allow you to show and hide different parts of a layer. However clipping masks use the contents and transparency of a layer to determine which parts of the layer above it remain visible.
How to attach a Clipping Mask
On the bottom layer add a background layer, on the middle layer add the mask, and on the top layer add a photo.
Select the Photo layer (top layer), right click to bring up the sub-menu, and select “Create Clipping Mask”.
And magically, the clipping mask hides the shape on the background layer and reveals the shape on the photo layer – instant PhotoArt!