Supersets are a useful weight training method that allow you to do more in less time, thereby increasing the metabolic requirements of your training. This in turn means more calories used while you are training and in the period after.
Super-setting normally entails choosing 2 (or more) exercises for muscles that oppose each other and alternating between the two exercises. You could, for example do the seated row for the back and the dumbbell bench press for the chest. Your superset could look like this:
A1. Cable Row
A2. Dumbbell Bench Press
Rest
A1. Cable Row
A2. Dumbbell Bench Press
Rest
A1. Cable Row
A2. Dumbbell Bench Press
You would normally move straight from the cable row to the dumbbell bench with no/minimal rest.