This book is designed to have a long shelf life, and as such, the way that it is used will change as you gain experience. The book is also designed for nonprogrammers as well as technicians who have also had some exposure to programming.
Different readers will have different needs, so there are different paths through the material, depending on individual circumstances:
Beginner: No exposure to programming.
Some Knowledge: Some exposure to programming, with non-C languages.
Intermediate: Understands the basics, can create programs.
Learning Reference: Ongoing study.
Professional Reference: Off-the-shelf solution seeker.
Of course, as you gain confidence in programming, you may well find yourself moving from one of the categories ...