Canning food at home involves using either the boiling water bath or the pressure canning method. It's possible to use the boiling water bath for fruits or pickled vegetables, but all other foods are low acid and necessitate pressure canning.
To can using the water bath method, heat the jars in hot water while preparing the ingredients. Use a jar lifter to remove a jar from the water. Fill the jar with the ingredients, making sure to leave the recommended head space. Clean the rim and threads with a damp cloth, and place both the lid and the rim on top.
Once you've filled a jar, place it in a canner and fill more jars. Once the canner is full, lower it into a pot of water. The water should cover the jars by at least 1 inch. Bring water to a boil, and process the jars according to the recommended instructions for the specific food.
For the pressure canning method, prepare and fill each jar as for the water bath method. Place each jar in the pressure canner. There should be at least 2 inches of water in the canner.
Lock the pressure canner lid, but leave the vent pipe open. Heat the water to boiling. Let steam escape through the vent until a steady stream appears. Close the vent, and process the jars according to the recipe. Remove the canner from the heat, and allow to cool until the pressure returns to zero.