Given four layers which have a black background, and areas in those layers that are clear, is it possible within PS to combine the layers so that I have just one layer with the four clear areas combined against a black background?
Are the clear areas transparent? If so, you can combine them, but you don't want to flatten the image, just merge the layers. Hard to tell exactly what you're doing without seeing a screen shot. Is the black background the background layer or black on each of the layers? Can you post some screen shots?