Bill, our 2015 Expedition and all of the documentation is in Florida. We are home in North Carolina, so I'm doing this from memory. I'm also assuming that your Expedition is wired the same as our 2015 38K model.
In both the front electronics compartment (above the instrument panel), and the rear one (behind the bedroom TV), you should find an unconnected end of coaxial cable and an unconnected HDMI cable. In each compartment, connect these cables to the corresponding input/output connector on the back of a Dish receiver.
The Winegard antenna comes preset for DirecTV. To program it for Dish, you will need to remove the dome, locate the "numbered" mini-switch and change the switches as follows: move number 4 and 7 down, leave number 8 down. The rest should be up. See http://www.manualslib.com/manual/815165/Winegard-Roadtrip-Mission.html?page=3#manual for a picture of the switch positions.
Fleetwood uses HDMI splitters to power any additional TVs. In our 38K, the front TV and living area TV are both connected to the front satellite box, so these TVs will always be on the same channel if you have selected the satellite TV input on both TVs. The bedroom TV and the outdoor entertainment center TV work the same way. Of course you can change the source from satellite to DVD or Over The Air (OTH) on any TV by selecting the appropriate TV input setting.
Hope this helps.
Steve