Setting up Nuke at home

I have been having trouble getting the lighting in my virtual environment and the footage to match up There is a bit of a black boarder on everything (especially the tuba or anything chrome), and the contrast on the colors has always needed a lot of tweaking. The guy from Renderman said a problem mixing linear RGB and sRGB  would cause a similar problem, and Adobe After Effects could not deal with linear RGB. So I downloaded Nuke, and I am trying figure out how to use it now.