I have jars with clips and rubber seals and I can't work out do I put the rubber seals on and fasten the clips before I put them in the oven? I am worried the rubber seals will melt but can't seem to find anything to tell me.
Also, do I need to leave some 'head room, and if so how much??

Last year it all bubbled out but maybe that was because I hadn't put the rubber seals on

Any help appreciated, I have various bits of info on bottling but can't seem to find the answers to these questions.
