Help please

I have a Ray marine set-up C120 etc, I have just bought a shipmodul NMEA multiplexer and a Yeoman at the boat show, I started reading all the manuals and have gone into info’ overload.

Can anyone direct me to a schematic on how to get these talking to each other and where on the existing system I can get a NMEA feed from and back into it.

Is there any pc software that makes use of NMEA information and displays, I am already running maptech.

Much appreciate the help in advance.