A cheap volt meter would be your best friend like this:
http://www.harborfreight.com/7-funct...ter-92020.html That way you can trace the circuit to see if you are getting current.If you don't have some one to hold down the horn ring wrap some duct tape around it while you test,look for the wire coming out of the steering column under the hood by the firewall check it first then on to the relay.Here is a wiring diagram and what the relay looks like.