You bought what is more or less the bible for people starting in that field.
It’s possible that you might be missing some intermediate steps before you can approach the subject, be it some maths or programming notions and experience, or something else again.
It’d be helpful to know where you stand skills and experience wise, and what you’re trying to achieve.
Ever written a shader? A deformer? A noise function for something? Familiarity with basic calculus?
If you haven’t touched any of those you’ll need to take a couple steps back and build yourself up to a point where you can approach some of the stuff presented in the book before you worry yourself with proceduralism as a subject standing on its own.