aftermarket volt/alt gauge wiring help

Hello all. A quick and im sure a easy question for most. I have a after market alt/volt gauge i want to install. 2 wires Equus guage set up. What is the easiest way to hook up the wires? I know one is grnd but any ideas for a almost idiot?????????? No instructions at all with guage. Looked it up and hell, kind of confusing.Any help is appreciated.