I just installed an Aprilaire 550 humidifier on my Goodman furnace but can't figure out how to wire it. The furnace has a control board which has a 24 volt HUM terminal. My humistat has two terminals. I am looking for a very simple explanation on how to wire this thing up.

http://i48.photobucket.com/albums/f250/rickdb1/humid-1.jpg

At the furnace, one wire will go to the 24 volt HUM Terminal and the other to the 24 volt ground...