Installing a horn button in Racemark wheel

[procan]

I have a racemark wheel with the horn button missing. I checked under my front fender, and the horn is still there, so I'm guessing this should be a somewhat straight forward hookup. I need a horn so my car will pass safety.

I'm not sure if the button size on the Racemark is the same size as the MOMO, and I also have no clue how things are supposed to go together in there. I remember a thread I read on pelican going over horn button instals, but I get so many hits when I use the search feature it is hard to sort through them all. Any help would be great.

Here is a picture of my wheel:



Inside where the button should go:


What I think is the wire the horn button should hook up to??? If not I have no idea what this random wire coming from under the dash is:

[procan]

For what it's worth, I think I have the same Nardi adapter as in this thread: WTB: Early Momo Steering Wheel Hub "Non Rib Style".

The hole in the middle of the wheel is 2.25", and I'm under the impression that the MOMO button is 2". Can someone please confirm this?