"of" structures are relatively rare. We would almost always say *"My book."*. In general, possessive structures like "my book, your book, his book, her book, our book, their book, Bob's book, the fat man's book, etc" will be much, much, much more common than "the book of Bob."

Assuming that you're trying to say that the book belongs to you, you generally would say "my book" although you could also say that the book "is mine." "This is my book" "This book is mine"