The hardest part of this assignment is to get the camera to focus on the the main object/person and make the background blurry.
You change the aperture level. The lower the level the better shallow picture you get. The higher the level the better deep DOF.
My favorite photograph is the one of Charles in DOF deep because it came out the best and almost everything is in focus.
I like taking peoples portraits because if you get a person at the right angle you can make the person look cool and ver focused.