You need to disconnect the vent lines from the boat and use them to fill the bags then install new vent lines from the bag to the boat. The rear bags are pretty easy, the KGB one is a little trickier install but if you start with the rears it should be pretty straight forward moving forward.
Depending on year you may have to reprogram the pumps, some years have timers some don't.
Do you have the bags, connections, hose and clamps?
Here is a link to an install one of our customers did, its the best step by step I've seen so far. http://www.mastercraft.com/teamtalk/...highlight=sacs