The next step is real easy. You just remove the supplied holder nut on the switch and put the switch through the hole you drilled and put the nut back on the switch securing it to the ballast housing. Reassemble the balast and you now have a switchable HPS/MH ballast. I usually test it to find out which side is the HPS and mark it with a sharpie. Test with the HPS bulb as it will not fire if the ignitor isn't in the circuit. Voila, you are done