Horn problems..95 Gt

I was told that the horn was all hooked up correctly, but that the horn itself does not work and needs to be relaced. Can anyone help me and tell me where the durn horn is on this model and is it a easy fix that my son and I could do, or do I need to take it somewhere to have it done?? Can I get a horn from any auto parts place or wrecking yard? Car needs inspection asap, like Monday and with out the horn working it will flunk inspection. Please help me?????

Thanks so much~