This is about as simple as it can be made. Follow
THIS LINK and see if you can figure out what they are talking about. If not you could bring the parts Friday and I will slap it together for you. The only difference on your dual stage is that you will have another set of NO/C/NC connectors for the second stage. You will want to connect the black wire of the outlet side (not the plug side) of the cord to the NO post and the white should just be connected to the other whites.
I haven't wired a Ranco controller but from looking at the diagram that is what I gathered about them.
All the controller does is touch the black wires together at the right temperature. If the sensor is too cold it closes the connection for your heater and too hot it closes the fan/chiller connection. It is as if you have the white wire still connected and you touch the blacks together.
NO means Normally Open ... the wires arent closed until the temp is reached.
C means Common ... this is where the black wire goes IN.
NC means Normally Closed ... The wires are closed until the temp is reached.
When you turn one of those little roller cord switches that turn on a lamp it just opens or closes the black wire to stop the light bulb from getting electricity. You are doing the same thing with this controller using temperatures.
Oh, BTW you won't need the second plug part from cord number 2... just plug #1 and socket #1 & #2.
Hope that wasn't too confusing.
-- Kevin