I remember that I did it exactly as the book says and it worked fine for me.
If EF cannot figure out Primary Keys of your fields, may be you should take a look at your model classes. You can either use "naming conventions" - fields with "id" in their names, or apply attributes - [Key]
Code:
public class Book
{
[Key]
public string ISBN { get; set; }
And, guys, I do not want to offend anyone, but the book is in "Professional"-series. The readers are supposed to have certain experience in .NET and in Web-programming. The book does not take you by the hand and goes exactly "step by step" as books for beginners do.
If you find it difficult to follow its tempo, may be you should start with grasping the basics of ASP.NET MVC. On asp.net/mvc website there are FREE Pluralsight videos by Scott Allen. Take some time to watch them and I think you will find the book easier to follow afterwards.