Temp. probe working, but haven't gotten the high temp. alarm to activate the buzzer.

Also, for the low level alarm, I bought this relay and I think this transformer to convert from 120V to 12V. What terminals do I use on the relay? My thinking is power to the relay, to the transformer, two wires out to the float box, and I think it's the COM terminal on the relay sends the signal to the buzzer. I was playing with it last night, but didn't get it to work.