You can get one with racks or without. We use one without and just place the jars over each other. Check the instructions that came with your canning pot. Just make sure that your canner comes with a thermometer or with a way to push in an elongated thermometer. We use a large pot because we can a lot in one go and I recommend you get one that is large enough for all your needs. Don't use pressure cookers, they are not made for this job. There are pressure canners too, but that's a whole different topic.