Trading is the practice of swapping gold for items with other players. Only players level 3 or above can use the trade feature, and a 10% "gold tax" is placed on every transaction.
To trade with a 'non-friend', click on your profile tab, which is the symbol above Camp and Inventory, this will show your trade link which can be copied and pasted into forum threads for trading. This is used when you are buying.
If you are selling and need someone elses trade link click on their name. This will take you to their face book profile. The page address ends in a number which is theirs. Copy that number. Go to your own trade link, as explained above, and this will give you a Levynlight trade link. By replacing your number with the other persons number you have their trade link. This allows you to make selling trade offers to people who are not 'friends'.
Player Shop is a feature that enables Seekers to post trades on their own profile. This means that other people who see your profile can trade with you by accepting an offer posted on your profile. To post offers in the Player Shop, simply start a new trade  and mark the option "Player Shop:".
 - Trading FAQ