You both may already know all this, but I've had a number of questions from BPers about layers in the past few days, so I thought I'd make a few remaarks about it.
Layers are really extremely simple (once you get the hang of it). Well, they can be complicated, but they can also be pretty easy.
The first thing I do when I set off to work on a picture is make a duplicate copy to work on (in case I mess up!) and the very next thing I do is to make a duplicate LAYER to work on. Then all the original unchanged info is available in case I need it right in the same picture (readily available for access). This also immediately protects the picture from data loss.
I use adjustment layers to change brightness and contrast, levels, hue and saturation, warming etc. You may already know this, but those things work just the same, but they don't bruise any pixels and if you don't like them, they can be easily removed or readjusted at any time without affecting later work (you don't have to back up and do things over). You can clone from one layer to another, add things and subtract them again, etc. After you play with it, it becomes very intuitive and not much different than not working with layers except that it is so much more versatile.
If you need any help let me know. The easiest thing of course is to have someone show you.