Humans have been cooking their food since the dawn of mankind. Over the centuries we have established an amazing amount of techniques and apparatuses to accomplish this task. You might be surprised to discover that with a clean garbage can and some minor modifications, you can smoke, bake, braise and grill. A galvanized can is one that has been treated through a electrochemical process which adds a thin layer of another metal (typically zinc) to protect it from the elements.
Drill a hole in the top of the lid and install the temperature gauge by pushing it into the hole. The hole needs to be the same size as the gauges probe. Install the gauge near the center of the lid for the most accurate readings.
Pour 3 to 4 inches of sand in the bottom of the garbage can. This will provide the insulation for the charcoal so it doesn't burn a hole through the steel.
Drill six 1/2-inch holes in the bottom of the can just above the sand line to provide oxygen for the fire.
Pour 20 to 30 charcoal briquettes on top of the sand and light with either lighter fluid or a charcoal chimney. This should provide a direct heat of 375 degrees Fahrenheit. You many have to adjust the amount of charcoal to reach your desired cooking temperature.
Insert the cooking grate into the can. It is important that the grate rest slightly above the center of the can. You may have to insert three screws through the can at the desired height to give the grate something to rest on.
Place the food on the grate and cover with the lid.
It will take several cooking sessions to perfect the relationship between the amount of charcoal and the desired temperature in the can. To smoke, add a handful of wet wood chips to the charcoal during the cooking process.