Horn parts missing, what should I do?

[1990festiva]

When i bought my Festiva, the horn didn't work, and upon inspection, both the horn relay and horn are gone. I cant tell what wires are supposed to got to the relay, but i have found the wire for the horn under the hood. Can any one tell me what Wire in the steering column goes to the horn button so i can wire in a new relay, or give me some other advice for sorting through the wires under the dash?

[MTec007]

use a cirucuit tester like http://www.amazon.com/Equus-3410-Cir.../dp/B0014DINF6

[JohnGunn]

OK, here is the wiring for the horn circuit.

Black wire from battery to main fusible link.
White wire from main fusible link to stop fuse.
Green/white wire from stop fuse to two terminals on horn relay.
Green wire from horn relay to horn switches in steering wheel.
Green/red wire from horn relay to horn.

Stop fuse services both horn and brake lights, so if brake lights work fuse is OK.

John Gunn
Coronado, CA