Clay, the Surface layers work similar, in the way I see, it to photoshop layers...the bottom or most recently added covers all untill you adjust it's Distribution either in the Surface layer itself, or by adding a Distribution shader in the Mask by shader area. Layers can be moved up and down with the Move arrows as well if you want a layer under a different one for any reason. It was, to me, more confusing at first using the node pane but in many ways it's as fast or faster and you can see things a bit better. Once you have a stack of Surface layers you can alter each layer further by adding Child layers to each main layer and they can be adjusted so they interact with the main layer using the same tools. Was this at all helpful...i seem to be rambling.
