Trading with players from others guilds

I am in the sin guild. Say I want to trade with someone in psycho or rancor who posts available trades and their player Id on the forum. How do I execute the trade? The game does not let me input their player Id anywhere that I know of. Am I missing something? and how do I do this?

Thank you

Well you can tell them to post a message on the highest ranked player's wall and then you can go and click on their name. So for example, right now Aids is the highest ranked player so if you want to trade with someone, just tell that person to post something on Aids wall and you can go and click on their name.

thank you so much. very appreciated