Again...no step 1 and step 2. But then your imaginations can go crazy!!!
In the "wholecloth" painted background it can either blend in as part of your whole piece or simply provide the appropriate feeling to the real stars of the piece.
Here is an example of a painted wholecloth background that is meant to blend in as a supporting actor in this piece. It started a one of my photographs and it needed a definite all over background.