Horn problems

Maybe the horn is bad. Test for power to the horn.

How do I do that?

you'll need a multi tester , if you're going to work on your car there are tools you will need , the horn probably grounds to the frame/body , check that too , you can tap on it also it may sound off then you 'll know it works and the elec. contacts are bad . You could have swapped a similar relay to see if that was the problem and bought the tester with the $$ you spent