The Processing book’s Chapter 1 is a general introduction to computer science (with an emphasis on creative coding) and to Processing. Those interested in the history of Processing may wish to read the whole chapter, but this background knowledge will not be expected on assignments or in class.
The Quick Tour section (pp. 12-32) serves as a nice reference to the interface for Processing, but I find that it makes for boring reading.
Instead, Chapter 2, pp. 33-48 (up to but not including Algorithmic Face) will directly prepare you for class 2.