Not too much. Don't get carried away here, but knock the hell out of the big stuff, anyway, and take some of the small stuff with you too. Don't go nuts here, we can change it later if need be. N ow, make another copy of the background layer, and move it to the top of the stack. It's now the top layer, of the 3 layers you have.
M ake another copy of the background layer.
You now have a total of 4 layers. Put another way, it is the second layer from the bottom. S top right here and be sure things are correct, because if your layers are out of order, nothing will work in our next step. This will both select it, and open the layer options window for that layer. H ere's what we're doing now.