It really isn't hard. The controller should come with a wiring diagram but all you really need to do is buy a 3-prong extension cable and cut it in half, then wire up the "male" half going to power, and the "female" half going to the fridge (or whatever you are controlling). Also you have to connect the probe but it's only two wires and it doesn't matter which wire is connected to which pole.
The only thing is to be careful which controller you have. MAKE SURE your controller says it's for 110/120v AC and not 220 or something else. Should say on the board where you make connections and set the jumpers.
EDIT: Here's the document that SHOULD come with it but you never know. Please note the diagram on page 3.