It's pretty straight forward to connect the units ..... beyond that, it depends on what you want to do with the network. Waypoints will pretty much share between units automatically ..... You can do transducer sharing also, and that setup will show up in the network setup menu once the units are connected.
If you do a Google search for Humminbird Ethernet Manual you will find a PDF manual. There may be some old versions floating around out there, so get the newest one you can find.