avatar_kiyoshi: Thanks. Right now it does not use anything. To make this a safe marketplace to trade I will have to verify accounts, and verify trades. How? I don't know yet. Maybe you could help me figure it out, but the idea you came up with is good, and a necessity.
*snip*
Use an escrow service, you should hire a professional escrow, here the list:
https://bitcointalk.org/index.php?topic=855778.0use an escrow is the important thing for make a trade, it's can people safe to use your site.