I've begun teaching myself how to play the organ, but right now I only have a piano book...?

No. You cannot learn how to play the organ with a piano book. Try to get a good organ method book. Above all, one that has organ excercises, because they are different from the piano... For example, so not to lift abruptly the keys, there are exercises that teach you how to "substitute" your fingers carefully , so they can play the next chord without "jumping", or cutting off the sound short...Hard to explain, but you will see. If you can get a teacher, try to get one. Perhaps it wont take you that long to acquire a good organ technique..it's full of tricks, really. Good luck..

A traditional two manual organ will have 122 keys whereas a piano has 88. Of course there is duplication in the organ, both manuals cover five octaves; sixty-one notes each. ... and the pedal klavier. You need both an organ method and literature to play organ. You'd also be wise to seek an organ-specific teacher. Hard to find indeed. The next best solution might be "organ tutor 101" a computer-based organ tutorial and method book by Brigham Young Univeristy. The OHS (Organ Historical Society) also has method books, folios, sheet music, and a wealth of other organ-specific information available. ... best of luck in your pursuit of organ music.

You can't really teach yourself to play the organ out of a piano book. Organs do not extend the full 88 notes that a piano does, but by using various stops, the pipes can produce sounds octaves lower or higher than a piano ever could. However, there is no physical "note" to hit for that. A lot of piano music DOESN'T work well on the organ... you'd be better off finding a book of organ music.