Diablo III no longer has the RMAH. Trading now is completely different on the PC version.
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While playing with friends, you might find items that better suit your allies and your allies might find items better suited to you. You will have 2 hours from when an item is found to trade it amongst friends that were present when the item dropped. This restriction doesn’t apply to gold or items of Common, Magic, and Rare quality.
Trading on PS3:
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"You have to be in a group to trade on the PS3 console. Click "select" for info screens. Move highlight to desired team mate and press triangle to trade, then press triangle to move to your inventory to select a trade item. Scroll to the item in your inventory to trade and click "X" to add it to trade window. To trade another item press triangle again to move to your inventory again and repeat until you are ready to trade and confirm trade by clicking "X" and then the other person has to confirm trade, if they are not paying attention no trade occurs until they confirm."
Hope that helps. PM me if you have any more questions.
Sources: battle.net