[jerry w]

Your gauge should come with wiring instructions.
One way:
Run the positive connection into "gauge" connection of your wiring harness. All your other gauges go back to a fused connection on the wiring harness.

Ground the Voltmeter, there should be a "ground" near where all your other gauges are grounded.

Finally there should be a wire for the light bulb on the ampmeter gauge, connect it to the Voltmeter light bulb.

Hope this helps.

Regards