At this point I like to "Save As" a .psd and give it a name like Les Paul v1 (as in "version 1") Once I do that, I right-click the background layer in the layer window and select Flatten Image. Right click it again and Duplicate Layer.
This time we are going to create a B&W layer above the color layer in the background and just like before, we'll use a mask to reveal the color body of the guitar only.
The above image has most of what you need to know at this point. You'll notice that by performing step one above, you'll automatically get a layer mask ready to go. You don't have to paint anything in the mask. You can certainly leave it white. In fact, many of the most useful adjustments are in the "pie button" ready to go. With a creative use of the layer masks and the menu of items in the pie button, you can do lots!
So paint away the B&W layer to reveal the Cherry Sunburst pattern in this classic Gibson Les Paul guitar . . .