It depends on what you want to do. I've done it a couple different ways...
My first one, i wired the Love controller to control an outlet. I then plugged the freezer into the outlet. It was very straightforward, but I lost the ability to use the light in the lid (not a big deal to me).
For my second one (my fermentation chamber), I replaced the stock temperature controller with the Love. I took apart the fridge, traced out the wires, and installed it. Took a little more work, but it was still relatively simple.
I then did the same thing with my lagering fridge...
So, if you want to do the latter... On the back of the fridge there should be a wiring diagram. It may be folded up and stuck inside a plastic bag near the compressor. If not, try to find it on-line. The key is to find out what wires do what. You'll need to find the existing thermostat and replace it with the Love, but in addition, you'll need a neutral to power the Love. Then it's a pretty straightforward thing-- hot to hot, neutral to neutral, and load to load.
That said, if you've never done this before, find someone with electric experience to help you. The results of screwing up could be catastrophic.