That photo is a 68 and wont' do ya much good because 69 is different...I don't believe you have a circuit breaker on the firewall as shown in that pic.
Here is what I believe to be my horn relay (in place of the convertible top motor fuse breaker). Also, the picture of my fuse box with my 20A circuit breaker jury-rigged into the upper left fuse. It is only labelled "Power Accy" with no Amp value
The black wire adjacent goes to the Switch on the dash.