I should clarify... I didn't mean that would be YOUR plot background story. It would be the plot background story for the series The Office. It's just another example of how a plot background story sets up the current plot. It's a prequel essentially, although it doesn't have to be novel length. The exercise is intended to get you to know your characters and situation a little better, to understand what motivates them, and as QueenNormaJean gettinPomsready pointed out, how your characters landed in the situation they're in that is your novel story.

YOUR plot background could involve the first time your main character met the unrequited love, or first realized his passion for radio.

Cheers,
Michelle