Welcome to Gaia! ::

hey there smile I'm sorry to say but you can only wear 8 rings at a time sad you can however change the rings you are wearing by going into the null chamber and opening your inventory

As for selling them on the market..... you cant to that either sad , they started "soul binding" the rings September before last so no one can sell them anymore, the ones you see on the marketplace are rings left from before they started soul binding them lucky people never equipped them or upgraded them so they can sell them, and i wouldn't suggest buying one just in case you were considering it, its quiet silly since zOMG now spews rings like moby smile

Best of Luck

the second row is for power (ups ie ghi amps double charge orbs and revives) which can be bought at back ally bargains or on the market, the discriptions explain what they do