reverse light switch/ horn
 

haven't been here for a bit, im trying to finish up a few small things so I can enjoy the car this spring. i took it to a show last fall 400ish cars and entered it in work in progress got 2nd and so much attention it was awesome! anyways I have a question about the Miata reveres light wires I thought I set them to the side... but at some point cutting dead wires taped them up. so if anyone can confirm or help me out I looked in my Haynes manual from what it looks like I need black/yellow wire I found one wire from the fuse box under the hood that splits into 3 wires only a few inches from the box. it runs into the firewall under the dash. (this is my main issue I need to fix but)
I also cant figure out why my horn wont work green/red wire it works if I jump it but the button on the steering wheel wont honk it and I used a test light showing its not getting power. I can run new wires and button if I cant sort this but would rather use stock to keep things clean.

91 Miata t5 tranny

any input helps! these few issues and finish my exhaust and ill be burning rubber legally ;)
thanks
channing