I find the Livorsi fuel gauges to be almost useless. I played around with the Vessel View and entered all the tank data for the fuel, fresh water and waste tanks. I don't see any sensors on the fresh and waste water tanks so I'm pretty certain VV won't talk to them but how does VV tie into the fuel tanks? Thanks.

PS Both fuel tanks are pretty low -one needle is on the gauge stop and the other needle is on E. All the tanks on the VV show nothing.

You need a merc wiring harness that plugs into the engine harness. It connects to the fuel tank sender(s) at the tank. Your helm mounted fuel gauge(s) will be disconnected/disabled after you do it.