There are two horns (low tone and high tone). They are located inside the fenders, in front of the wheels, towards the top. Look by your cruise control servo on the driver side. They are tucked in there pretty good, so look carefully.
My horns didn't work from the day I bought my car. This past summer, I pulled the horn relay out of the under-dash "convenience center", and then pushed it back in. From that point on, the horns have worked fine.
Go figure.