Help with sig

Ok im doin decent so far :

1 question: When im using a brush for the background and the brush is somewhat over the character, i click to use the brush and it covers my render. How do i make it not cover the render?

mess with the opacity and flow until your satisfied

don't brush right! on render layer
add a new blank layer
use thing called an eraser(e)
since you added a new layer to brush on.. change its blend settings.. to color dodge and it will look shiny depending on your backround

brush on a different layer and put the render layer on top of all the other layers