it is like a court mediation process. you file a claim with your side of the story. they contact the seller to ask his /her side of the story. if the seller does not respond, they will decide in the buyers favor. after the seller has time to respond, then they decide the case. ussually if the complaint is for not recieving an item, they will ask the seller to provide a tracking #, if the seller cannot, they will decide in the favor of the buyer.
this is why they have shipping through paypal, so a seller has no excuse to not have a way to prove the shipment.
ALL OF THIS INFO WILL BE EASIER TO FIND ON PAYPAL.COM THEN BY STARTING A THREAD ON NEWCHOOLERS.COM