Here are the steps: Line the bottom of the pan with aluminum foil. Set the silver object on top of the aluminum foil. Make sure the silver touches the aluminum.
Heat the water to boiling. Remove it from the heat and place it in a sink. To the hot water, add about one cup of baking soda for each gallon of water. (If you need only half a gallon of water, use half a cup of baking soda.) The mixture will froth a bit and may spill over; this is why you put it in the sink.
Pour the hot baking soda and water mixture into the pan, and completely cover the silver.
Almost immediately, the tarnish will begin to disappear. If the silver is only lightly tarnished, all of the tarnish will disappear within several minutes. If the silver is badly tarnished, you may need to reheat the baking soda and water mixture, and give the silver several treatments to remove all of the tarnish.