First and foremost the exercises are designed as "chop" builders and to give you fluency going in and out of different sticking formats. Your only priority as a drummer is to play everything in time so work with a click track or metronome with every exercise. Below is exercise one on page five.
"Nothing too much interesting here", you might think? But wait!
As you can see the sticking is very simple at this stage, also there are no accents. Your task here is to get each stroke that you play the same volume as the one before it and that all the notes are evenly spaced apart. Start at a moderate tempo and not too loud. As you feel yourself gain control of the exercise take things a little faster and start to apply more dynamics, from very quiet to very loud and back again! Dynamic control is a must. These are only rules, from here on, you are limited only by the bounds of your imagination.
Next, and I hope this is obvious, get the thing moving round the kit. The more tonal changes that you hear going on the better. Don't just stay on the snare. As you move from drum to drum, try to hear that you have got a very even balance on each instrument.