Hello I will help you with your question,
If you supplied power to the horns and there is no sound it is likely that the horns filled with water and have corroded. There is a TSB to install horns facing rearward instead of the factory mounting. What brand of new horns did you install?
If you unplug the horns and work the horn switch does the relay click or close? Does the fuse still blow?
Let me know so I can help you
If you unplug the horns and the relay see if the fuse blows when you press the horn button. It should not as it is not connected to that side of the circuit. Use a paperclip to connect the #30 and #87 pin socket of the relay (horns still unplugged) and see if fuse blows. If it does no the aftermarket horns are the problem and the originals were likely corroded.
Some aftermarket horns need to be reconfigured to operate correctly.
Start with the horns out of the circuit and get the relay/switch and fuse working correctly then work on the horns them selves. You can install a testlight into the horn connector socket to take the place of the horns and that will give you a visual indication.
If you want to save on fuses you can wire a turn bulb or other 12 volt bulb and plug it in place of the fuse. If the light comes on you have a short which would blow a fuse, if the light does not come on you either have no load on the circuit or it is working correctly.
You need to break this circuit into pieces so you can see if you have a problem in a connector, the wiring or the horns so unplug the horns to start and work from there on the relay area.
Let me know how I can help you with this