This plan is using phases of microcyles. This means as you go through each stage, you'll be stronger, so you will have to increase your weights by 5, 10 or 20 pounds from phase to phase. This increase in weight but repetition in reps will confuse your muscles causing them to the new rigors.
Phase 1:
For the first week (Microcycle 1) use a weight that limits you to 15-18 reps.
The second week (Microcycle 2), increase the weight a little, ussualy by 5 lbs, and decrease the reps to about 10-12 reps for each work out.
On the third week (Microcycle 3), increase the weight again and decrease the reps to around 6-8 reps.
On the fourth week (Microcycle 4), increase the weight, for the final time for this phase, and decrease the reps to somewhere around 3-5.
Phase 2:
Phase 2 is just like phase 1 but you will notice that you are stronger than in the first phase. Because of this, you will increase the weight you are lifting but keep the reps the same.
Phase 3:
Phase 3 follows the same concept of phase 2, just increase the weight because once again, you will be stronger then the past month and hopefully by then, you will notice a dramatic change in your body.