Fill the container with water and add some washing soda to the water (not sure how much) so that it will conduct electricity. Clip the positive battery charger cable to the spoon (anode), and the negative one to the object you would like to clean (cathode). I use the cheap alligator clips to hang the object in the water. Make sure the anode and cathode don't touch.
Turn on or plug in the batter charger. I am using the trickle charge mode. You should see the cathode start to bubble. It is making hydrogen, so keep the area ventilated. I have left objects in there for 24 hours depending on how much rust needs to be removed. Check on the object occasionally washing it off. Eventually the rust clumps will easily fall off.
Caution: This process can get the tank very hot. I melted the first container I tried, so be careful.
Here is a good site that talks about electrolysis