Hi!
The first thing I'd recommend is to purchase The Ball Canning and Freezing Blue Book. Gosh, the guidelines change every year, it's a good thing that my Grandma didn't know she was doing it all wrong!! :?
Cold packing tomatoes is very simple.
Take clean, blemish free tomatoes, blanch for ~2 min. immediately shock in ice water. The skins will then slip off easily, halve or quarter depending on the size. Pack into quart canning jars (make sure no cracks or chips) pack fairly tight to 1/4" from top. Remove any air bubbles. I run the handle of a wooden spoon into the jar to release any bubbles. Add 1 tsp. salt, if desired. No other liquid is needed. Clean top edge of jar, place canning lid and ring, tighten. Into canner or other suitable pot, add water to 1" above jars. Cover and process 45 min. Start timing after water comes to boil. Remove allow to cool, etc.
Hope this makes sense and helps!!!
Have fun!
Deb :-)