I have done tomatoes many times, and this is the way to go. I used to go to a U-Pick field in the morning, and then go to a County Extension Cannery to finish up. These are not around any more. It is like Pam said, get a book, crush them up a bit in a pot and boil, then heat them up in the jar with a water bath for the time stated, take out and cool. when the lids pop, you know that you have a good seal. They store very well, but you will probably use them before too long. If you already have the sauce(gravy) made, just use the same method heating up in a water bath.