I read Sybil a very long time ago (after seeing the movie starring Sally Fields as Sybil Dorsett and Joan Woodward as Dr. Wilbur, her therapist), and I can't help you with a chapter by chapter summary. Not to mention that this sounds like a school project, and that seems a little like cheating.
I can tell you, though, that it is a very interesting nook, and I think you should really give it a try because you will enjoy it.