I can not say definitively how Lowrance networks are connected but would have to think its a fairly simple setup. I can tell you with my Northstar equipment, there are 2 wires in the power cable that are for NMEA 0183 networking. The DSC VHF radio also has two wires for NMEA 0183 networking. Basically there is a + 0183 wire and a - 0183 wire on each piece of equipment you want to network. The positive goes to the positive and negetive to negetive. This can be accomplished with a terminal block to add to later or as simply as wire nutting them together. I don't recommend wire nuts in marine environments, but you get the idea. Butt connectors will do fine.
Once you have the connections made, its a matter of reading your radios manual on how to turn on the network and what network you are using. As in my situation, I can pick from NavBus (Navico), NMEA 2000, or NMEA 0183. NavBus is a proprietary network for Navico units, Raymarine has SeaTalk, your equipment may have its own proprietary network that can be used if all components are of the same manufacturer. The NMEA networks are a standardized network that is capable of networking components of different manufactures.
So to answer your question, yes it is a simple two wire connection. Going through the menus on your GPS and radio and finding where to turn the networks on is the hardest part, which should be easy if you have you users manual.