You should start a bit further back, understanding how processing pre-processes a *.pde is very instructive:-
Processing caches it’s compiled java classes and a .java file every time you run a sketch, Apple will change where in the /var/folders/ directory this is. The fastest way to find the current location is to create a new sketch, don’t save it and press command+k which will open up the subdirectory of /var/folders/ where the sketch is temporarily stored.
Anyway should basically check that you understand what is going on, this will set you in good stead. Basically processing creates inner classes so that they can inherit methods etc from PApplet, you might not want to do that so, you need to know that you can access static methods using PApplet or instance methods on your instance of PApplet.