Open the hood, remove the plastic shroud covering the area between the grill and the radiator (pull out the center plastic pins, and the larger part of the pin will be removable). Remove the two large (and ONLY these) bolts which attach the headlight bucket assembly on the passenger side.
Note when removing the headlight bucket assembly do NOT touch any other screws or torx adjustments, only the 2 large bolts. Otherwise you will affect the alignment of your headlight.
After this is pulled up and out of the way, (no need to unplug anything), you can see down into a cavity between the inner and outer fender wells and the back of the bumper. The horn is there, near the bottom, typically mounted sideways with the electrical connections toward the front of the car.
Jack up the rider front side of the car. Remember to follow all safety guidelines for jacking the car into the air, and as always put on your rear brakes to further secure the car from rolling while your under it. From the front riders side get under the car and remove the splash guard from in front of the tire. Look up right behind the bumper, and you will see the horn attached sideways to a bracket. Unscrew the one holding nut, and then disconnect the wire from the horn assembly. Pull the horn out, and that's it. To check to see if the horn itself is faulty, use a jumper wire to jump the connection to the battery. Assembly is the reverse of disassembly.