i know this is a stupid question, but how does a-z work exactly. i mean i never had to use it, but still would like to know
If the item you ordered is not as described, you need to contact the seller to try to fix the problem. If the seller doesn't respond or attempt to help (in 72 hours, I think is the Amazon rule) you can file an A-to-Z claim and then the seller has the opportunity to state their side of the story, why they didn't respond/accept a return, etc or they can issue a refund and close the claim. Amazon will look at the information provided and make a decision, which on average is weighted in favor of the buyer, but not always.
It either is found in favor of the buyer or seller, or if the seller really isn't at fault, they will find in favor of the buyer, but pay for it themselves. The latter are the ones that will eventually get you in trouble, as it's basically saying "your claim doesn't add up, but we'll take care of you this time."