And layer order:



I want to use some color correction:
So create a new adjustment layer on the top of the layer box.



Use Gaussian Blur on this layer.



Make a selection using rectangle tool.



Copy this Square layer and make one of them smaller that the other using CTRL+T keystroke.



Here is what we got:
I've changed the color.







Layer 1 settings:















RESULT:

It's actually hard to see, but there is difference.