What I learned:
I had a basic understanding of what the numbers on my lens meant but until I actually took pics using the fstop and the focal lenth as on the lens did I grasp it better.I still need to do this with my other lenses so I get it down pat.
Using a lens at 200mm is not the best lens to get a shallow depth of field. I took several pics but these were the only ones that showed any noticable shallow depth of field