Mark is right, read up on it. I mixed baking soda about a 1/3 to half a cup with water and mixed it in a bucket. I had a plastic plug, like a lid that I shoved into the fuel sender hole. A small funnel would work. I set the tank upright and poured in the solution, or "electrolyte" and filled it to the top with water. The plug was shoved in tight enough to somewhat seal the fuel sender hole. I had a 1/2" steel rod or "anode" that I shoved though a hole in the plastic plug making sure it did not contact the metal tank. I used my battery charger for power and hooked the positive clamp to the "anode" and the negative clamp to the tank making sure it had good connection. Make sure you make your hookups before you apply power so you don't create a spark. Also, make sure you have good ventilation.
On my first go around, I installed a #9 wire through the filler hole and ran the length of the tank. When I pulled it out, it was nearly ate down to a thread. I did read that through the process, the rust is more or less traded out for the metal on the anode or something like that. I'm kinda talkin out my other end on that. :shock:
If it would help, I could set it up on another tank I have a get a picture.