I cant see your file. BUT the way I did it was, I had looked for the oem horns and tapped into one of them. ran the wire back to the cabin where I had a toggle to turn it on and off, and then ran it back to the solenoid. That sound ok?
You have to run wire from the cab or inside ya car down to your existing stock horn. normally two terminals on the horn, one of which is grounded to earth.
you connect your new wire to the terminal that is NOT grounded.
On the switch you connect the other end of the wire to your new switch. If you have a three pole switch you need to connect it to the common, common Normally marked with a “c” and the terminal in the middle. Then it does not matter which terminal you connect your other new wire, that goes to your new horns to. (basically with if its the wrong way up turn the switch round)
If you consider that to be too problematic you can always take it to an electrical store and have someone do it for you or just use an alternate horn button just for your other horns. If you want pics, ive got em.