Layers is where I have trouble. I can do things with fixing exposure on all or part of it, I love the clone stamp tool, but I do it all on the same layer because I find the layers too complicated... ecurbh ~tries~ to help me.
It is just a big stack of transparency sheets more or less. it helps to turn off the ones you are not working with so they don't cloud what your are editing. I make lots and lots of layers and just turn off the ones I don't like. I was doing line art colorizing mostly so layers were really important. Photo editing they are less so, but still really handy.