Link to a YouTube post of Pete Seeger singing "Which Side are You On?" with a participating audience. Notice the different right-hand styles for different parts of the song, and how smoothly he changes his rhthmic approach. It's a superb "how-to" lesson in self-accompanyment by probably the best ever at it.
http://www.google.com/search?client=safari&rls=en&q=which+side+are+you+on&ie=UTF-8&oe=UTF-8