The book details the story of Oblivion. It gives a little background on the characters such as Mehrunes Dagon. It then goes on the talk about Cyrodiil, and the cities that Cyrodiil holds. Saving Cyrodiil after the break out of the Daedra from the realm of Oblivion, after the death of the Uriel Septim VII, is also discussed.
Character Classes: Choosing your Race, Sex, Abilities, Skills, and Birthsign
This section discusses each race's strengths, weaknesses, default ablilities, and attributes. It works you through how to create an ideal character for you. It tells you which races best fit in which Factions. A detailed account of Birthsigns, and how to create certain characters that best fit your personal fighting style are discussed.
How to use weapons, and weapon skills, is detailed. Awesomeness
How to aquire spells, and use magic in combat is discussed. This section also has an all-inclusive list of every spell in the game (except for those you create).
Crime & Punishment
Types of crimes, being arrested, how much to pay the court, and jailing sentences are talked about.
How to become a vampire; a vampire's powers, and weaknesses; and problems with being a vampire, are discussed.
A detailed list of enemies and creatures, along with all of their abilities, is in the section.