A zipper is easy to operate, right?
Well... there really is a correct way to do it, in order to keep the teeth from being stressed and/or breaking, which is the main cause of the zipper replacements that I do.
Ready for it?
Go to the top of the zipper and fasten the hook and eye first! That will hold the dress together while you zip up through the waist.
If there’s no hook and eye, you need one. Sew it on yourself, or take it to a seamstress.
By the way, I offer the hook-and-eye service free when I’m already working on a garment!