I've laid out a GENERAL overview of the process for you:

a) Buyer, Seller and Middleman join a multi-user chat.
b) Buyer and Seller confirm the trade agreement with the Middleman.
c) Buyer initiates the trade with Middleman from the multi-user chat window and gives the items.
d) Middleman verifies that he has received the items and informs the Seller to proceed with payment.
e) Seller confirms money has been received and confirms that Middleman may give items to Buyer.

– Transaction Completed –