The water out of the overflow should go, first, through the skimmer. Once the water has gone though the skimmer, it will flow into your return pump. Connect the "out" from your return pump and then connect it to the "in" of the sterilizer. Then, the "out" of the sterilizer will re-connect with your return line and then back into the tank. That way, it's going through your skimmer to remove the excess proteins and then through the sterilizer to kill and baddies.
Hope that makes sense!
Hope that makes sense!