Plan your canning project. Decide which fruit or vegetable you want to preserve. Also calculate how much fruit or vegetable you need to pick or purchase. Generally, 3 lbs. of fruit will fill a 1-qt. canning jar. Make sure you have all of your supplies before you begin.
Wash your produce in clean water, and then pat them dry. Examine each piece for any bruises, rotten spots or blemishes. Cut out all bad spots and send them to your compost pile.
Sterilize your jars and lids. First, rinse jars in hot tap water and then place them in your canning kettle. Fill it with water until the level is 1 inch above the tops of the jars. Turn the heat to high, wait for it to come to a rolling boil, and then reduce the heat to medium and let them cook for 10 minutes. Boil your lids and bands in a saucepan for 10 minutes while you are sterilizing your jars.
Cut your fruit or vegetable into the size and shape you want. If you are making applesauce, for example, peel and core the apples, cook them down and add sugar, cinnamon and any other ingredients your recipe calls for. You can chop tomatoes into small pieces or can them whole, but to dip each one into a pan of boiling water for one minute, then drop them into cold water and slip off the skin and remove the core. This method also works for peaches and other fruit whose skin you want to remove before you can them.
Remove your jars from their hot water bath with tongs, empty the hot water into the sink, and set them upside-down on a clean, dry kitchen towel. When the jars are cool enough to handle, fill them with your cut or processed fruit or vegetables. Take your lids and bands out of their hot water with tongs when you need them.
Fill jars to within ½ inch of their lip with your fruit or vegetables. It helps to run a dinner knife down the sides to remove air bubbles. When your jars are full, wipe around the lip with a clean, damp towel and then place the lid and sealing band on and hand-tighten.
Place your filled jars into the canning kettle --- by now, the water should have cooled a bit, which is important to prevent breakage of your jars, especially if you are packing cool fruit or vegetables into the cooled jars. Packing hot applesauce, for example, into warm jars reduces the possibility of breakage.
Cover your kettle and turn the heat to high. Watch it until it comes to a rolling boil, and then reduce the heat to medium and begin timing your processing period. Research how long it takes to process individual fruits and vegetables because each one has different requirements.
Remove your jars carefully when their time is up. With large canning tongs, lift the jars onto a clean kitchen towel out of the way of drafts. Wait for the satisfying "ping" the lids make as they cool and form a seal. When jars are thoroughly cooled, check that the lids have sealed by pressing down gently with your fingertip in the center of the lid --- if it gives any, it is not sealed. Put unsealed jars in the refrigerator and use them promptly. Leave the bands on your sealed jars when you store or remove them.