During weeks 1-4, you will be lifting in the 8-12 rep range. What this means is that you want to complete at least 8 reps but no more than 12 reps for each set. Week 1-4
If you cannot complete 8 reps, then the weight is too heavy and you should decrease the load. If you can complete more than 12 reps, then the weight is too light and you should increase the load.

Week 5-8
During weeks 5-8, you will be lifting in the 6-8 rep range. What this means is that you want to complete at least 6 reps but no more than 8 reps for each set. If you cannot complete 6 reps, then the weight is too heavy and you should decrease the load. If you can complete more than 8 reps, then the weight is too light and you should increase the load.

Week 9-12
During weeks 9-12, you will be lifting in the 4-6 rep range. What this means is that you want to complete at least 4 reps but no more than 6 reps for each set. If you cannot complete 4 reps, then the weight is too heavy and you should decrease the load. If you can complete more than 6 reps, then the weight is too light and you should increase the load.