Creating a Digital Background

I posted this image a long time ago on Smugmug, along with the instructions on how to create something very similar, but I never actually blogged about it. So, I thought I'd share it with you today.

First off, what is a digital background? A digital background is an image that is suitable for placing behind the subjects in an image; thus replacing the original background. The original background might be a green-screen, other studio backdrop, or some other scene entirely.