Wiring a shift light

[JT ZR-Won]

I had a small auto meter shift light in my previous '90 ZR-1. When I sold it I removed it and it has been sitting in a box for years. I just came across it and would love to wire it my (new to me) '90 ZR-1. The problem is I absolutely cannot remember how I did it. I believe one of my friends helped me do it originally.

Just being upfront, I am a complete electric wiring buffoon, lol. There are 3 wires coming out of the auto meter box.... black, red, and green. Where is the best place to tap into for ground, power, and RPM's?

Thanks in advance and I'm sure I'll have more questions.

Jay