find a manual and read it carefully...they can blow up.
My daughter wanted to can after she got married and while talking to her one day she told me about it and thru the conversation she mentioned the water level and then I asked her if she was doing water bath or pressure and she informed me she was pressure and I told her she put in way too much water she had filled it like water bath I informed her she was lucky it didn't "blow" for her. So really read your manual