1. Open the Buyer window
At the bottom of the Trading window is a toggle switch that changes the display from seller to buyer actions. Select Buy.
2. Review items for Trading
A list of the items posted by guests other than yourself will display. The left hand column of icons show what they are offering. The blue column to the right of this shows what want in exchange. The farthest right hand field displays your current inventory.
3. Make a deal.
Click the faded icons in the blue column to accept the the seller offer. A pink button will display when you have posted what the seller is seeking. Click this button to seal the deal. Your inventory will be credited with what the seller offered and the item(s) you exchanged will be deducted.