Trade
The trade options in Twelve Sky let you trade everything from Weapons to Silver. If you wish to trade items hold SHIFT + Left Click and Select the Trade option.

An easy way to make sure you are trading with the correct player is to check the name and level.

Put the items you wish to trade in the trade window and wait for the items you want to be added to the trade window. When all the items are correct press the Trade button and then the Confirm button.
IMPORTANT: Make sure you check the item level and the stats on the items you may be trading for!