Why does my horn not work?

Why does my horn not work? I have had my horn replaced and it lasted for about 1 year and now it once again does not work. I would like to do it myself now and not pay someone again to do a bad job. Where is the horn located and the associated wiring (I checked the circuits and relays and they're fine)? How is it mounted, replaced, and wired? 1998 Jeep Grand Cherokee - Inline 6 motor