Dear confused, you will need to have the proper lids to do your canning. Plastic lids won't really get the job done. Of course, scalding the jars will sterilize the jars, but you also have to scald/boil the lids and rings to be certain you have the proper sterile environment for canning your product.
If you mean "plastic" by the ring at the top of the lids, then you might have the proper lids. Still, we don't know for sure without more information.
"As a girl I had zero interest in the stove." - Julia Child
This is real inspiration. Look what Julia became!