Kevin, did you ever think that maybe no one understood the question? I suspect the question is deeper than "Where is the horn?" When I read it, I thought....a DUH...it's right under the hood. I never looked for it, but I guessed I could find it. Now, maybe that is a faulty assumption.
Maybe a better worded question would be one like:
"Hey guys. I am having a problem. I am having problem ____ with my horn, and I am trying to locate it. I looked under the hood and can't find it. Roughly where is it located in proximity to other items under the hood? Oh, and I have a <enter year> Sport Trac. Thanks!"
Again, though, I am making some assumptions. It is not clear to me from your question that you are looking for the horn, or the horn button, or why you would be looking for either, or where you have looked.
TJR