I dont have the same model refrigerator as you do, but I assume you have a panel in the freezer compartment that can be removed to expose the coils the same as I did with mine. When you do, you will see the defrost thermostat attatched to one of the freezing coils with those two wires you referred to coming from it. I have never done this before either, but I simply unplugged the defrost thermostat, unclipped it from the coil and replaced it with a new one I bought on Amazon for about 10 bucks.....and it worked great. Fixed the problem, though I had to buy some dry ice to store some frozen things while I was messing with it I had to melt the built up ice on the coils with a hair dryer a couple of times while checking it too, but finally everything worked. I left the panel off the inside of the freezer for a few days just to make sure it all worked as it should....but it was a great learning experience and it was a very cheap fix....
I looked online just like this to get some ideas on how to proceed, so just remember to unplug the frig before you begin and have fun......