Canning is one of those things that seems impossibly daunting, dangerous even (botulism, yeah!), but once you actually do it, it proves to be fairly straightforward. After all, once upon a time most women (and even a few men) had the skills, and used them to provide their families with something more than cabbage and apples and venison through the long winter months.
A few basics: Start by canning something acidic, like ratatouille, tomatoes, or pickles. Low-acid foods require greater care and longer processing time to safeguard against potentially deadly contamination. Do not go there until you have mastered the essentials.
Equipment: The most important piece of gear, besides the jars and lids into which your food will go, is your water bath canner, AKA a very large pot. Standard canning kits include said pot, a rack for jars, a jar lifter (a sort of clamp to move hot jars into and out of the water) and, possibly, a magnetic lid grabber.
While a canning kit is good, it's far from necessary: any old, large pot will do, and can often be found at a Salvation Army or yard sale. A jar rack is sometimes more of a pain than an asset, though a jar lifter is nearly essential, and if not found at a thrift store, is available new for under $7 at any kitchen-supply store. While you're there (or at any grocery store outside of New York City worth its salt) you can also pick up a case or two of canning jars, in whatever sizes seem appropriate. Small jars for jam, little pickles, individual servings of tomato sauce (not worth the hassle, really) and larger jars for, well, larger quantities of same.
So, you have a pot, a jar lifter, and an assortment of jars with two-part canning lids appropriate to the food to be canned. Of course, you have to prepare the food: cook up a big batch of sauce, or prepare your jam or pickles according to the recipe of your choice. Whatever fruit or veg you're working with, make sure it's fresh, and trim off any rotten spots—too much funk gets in the way of safe canning
As you near the end of the cooking, fill your canning pot two thirds full of water, and set on a back burner to boil. Once the water's boiling, take the lids off of the canning jars, and put everything into the boiling water—jars and lids. Let it all simmer for at least 30 minutes, to sterilize—sterile is the key word here: you'll want to have a couple of clean towels, and a nice clean surface to work on too.
Remove sterile jars and lids from the water bath and fill, leaving 1/2 to 1/4 inch of room. Wiipe the edge of the jar clean and dry, with one of the clean towels, and place the disc part of the lid on carefully, then screw the ring part on LOOSELY. Replace the filled jar in the water, and fill the remaining jars the same way, replacing in the bath as you go along.
Once the jars are all full, and the water bath bubbling, let boil for 35 minutes (actually, some people say the boiling time depends on the kind of thing you’re canning—for more details, you can head here), and remove all jars, leaving them to cool on your counter. Repeat till you're out of jars, or out of sauce, or both.
Once everything's cooled down, tap each lid—you should hear a taut click, not a hollow sound, if the seal is good. If not, refrigerate and use within a week or less. Tighten the rings, and fill your pantry.