The pattern of the excercises is that you do each body part in the following manner:

12 reps at a fairly low weight (like carrying groceries upstairs)
10 reps at an increased weight
8 reps at an even greater weight
6 reps at the heaviest weight
reduce the weight and do the same excercise for 12 reps
then do 12 reps of a different excercise but working the same body part.

I think the idea is that you do a compound excercise for the first 5 sets, and the one set that is different is supposed to be a more isolated excercise.

Compound excercises use more than one body joint. Work more than one body part at a time. The last set works just that muscle you are attempting to strengthen, such as maybe doing a bicep curl on the last set if you were working biceps.

I hope that makes it a little clearer.