I added a small onion and a few hot peppers.
You want to let it boil until it is no longer stiff but still kind of rubbery. Maybe 15 minutes(I didn't really keep track of the time). You are then going to put it in your jars. One thing I want to mention here is that you really have to work to get all the air bubbles out of the jars. Then pressure can for 25 minutes at 10 lbs pressure. I got 6 quarts out of these two heads of cabbage.