I found this on e-i-e-i-omg!
ven canning, so thought I'd share real quick.
Basically, this is what I do:
Preheat the oven to 200 degrees F.
Take clean, dry quart or half-gallon canning jars and fill them with whatever I am canning. Put them in a roasting pan, or other high-sided pan. I do this strictly for ease of getting them in and out of the oven - you can also put them on a cookie sheet. Once the oven has preheated, put the pan with open, filled jars (NO LIDS) into the oven and close the door. Leave them in the oven for one hour. Remove from the oven and, being very careful NOT to burn your fingers, wipe the jar rims quickly with a damp cloth and place clean, dry flats on top of the hot jars and screw on the rings. Let the jars sit and cool. As they cool, you may hear the telltale "ping" as they vacuum seal, depending on how quickly it works. Test for a seal. That is it. If a jar does not seal, which happens on occasion, I put that jar to the front to use first.