Basic information and techniques about playing a clonewheel organ, as distinguished from a weighted 88-key acoustic (or P120), hints about classic organ riffs, etc. Honestly, I'd look around the internet at sites like http://www.gospelkeyboard.com/ or http://showmethat.com and youtube, see what guys are doing. You'll learn some of those organ techniques a lot quicker seeing them. Then just listen. Winwood, Rollie, Argent, Emerson, and my personal favorite, Garth Hudson. Pick out what they're doing. You'll learn stuff a heck of a lot deeper if you learn it by ear than through the written page, it becomes more ingrained and organic.