Get one of those little 12v test lights. You know the thing that looks like a screwdriver with a point on it and a little clip on the end of a wire sticking out of the handle. Take the wire off the horn and stick it on the point of your test light. Then put the clip to a bare metal part of the car. Get someone to press the horn button. If the light comes on then the problem is with your horn. Get a jumper wire and put 12v straight from your battery to the + on the horn. (make sure the body of the horn is still touching the body of the car) If the horn does not sound then the problem is with the horn. If neither of these tests work then either you are not doing it right or both your horn and wiring are broken :) Hope this helps
Do you have power to the horn when you use a test light and push the horn button?