I got a standard push button switch for the horn. i drilled a 1/2" hole for the switch and installed the switch.

I ran a power from the fuse block to the push button switch (10 amp fuse)

I drilled a hole in the rear fender and mounted the Harbor Frieght horn. you can see all the wiring in place here.

Here is the relay i used for the horn. it is a common relay.

here is the side and wiring diagram for the relay

here is the bottom of the relay.

i ran a power from a new fuse to the relay and then to the horn and a ground.

i zip tied the relay to the coil pack so it will not bounce around. this worked great.