Several things--I work for U of Missouri Extension, and we get a zillion canning questions. You need to be safe, whatever you decide to do.
Water bath canning is for high acid or high sugar foods--fruit, jellies, jams. Pressure canning is for low acid foods, like beans, beets, meats. Tomatoes kind of fall in the middle, and adding extra acid is necessary for safe waterbath canning. (Just cause Mama or Grandma did it that way, and didn't kill anybody, doesn't mean you can do it that way!)
Pressure canners and pressure cookers are NOT the same. A pressure canner is larger and has something (a gauge or weight) that allows you to adjust the internal pressure. A cooker is generally smaller and not adjustable. You need the larger volume for canning, because the time that it takes to get the canner up to pressure is calculated into the recipes. A smaller cooker takes less time, so your food may not be processed long enough. (Lots of people call their pressure canners 'cookers', so sometimes it is a matter of common names. If you have a gauge or dial, and if you can put 4 quart jars in it, it is a canner.)
I do most of my canning in the pressure canner (I almost said pressure cooker--that is what I call it, but it is big and has a weight) because it is quicker and it does heat the kitchen up less than a big waterbath canner.
New canners (and by that, I mean canners made after about 1975) have multiple safety features that pretty much eliminate horrible accidents. They have a rubber or soft metal safety plug that melts when the canner overheats--if you run off and leave your pressure canner/cooker on the stove, you will come home to find the contents on the ceiling, but the canner itself will not explode. (Following directions and paying attention will pretty much eliminate the food on the ceiling problem!)
This site
National Center for Home Food Preservation | USDA Publications has everything you need to know to can safely (and stuff about freezing and drying.) As a beginner, be wary of internet recipes, granny's recipes and any books besides this one or the Ball Blue Book--
New Ball® Canning Products
Ball has another book with more tested recipes, but I can't remember the name of it right now--we have it at the office.
Use real canning jars--not mayo jars. Don't reuse the flat part of the lid--you can reuse the ring.
And enjoy--there is great satisfaction in hearing that little 'ping' as the jar seals, and seeing your hard work lined up on the counter. Of course, popping the top on a jar of summer canned tomatoes in the dead of winter is pretty cool, too!
There are lots of home canners on this board--don't hesitate to ask questions.
These two books contain tested recipes.
