If you want to sell your unwanted items, you can click a market vender to set a booth in the Market.

Put the target items into the booth and set the selling price.  Then all you have to do is wait for the buyers to come.  You can also stop selling the item by dragging it back into your cabin.

You can also click "Hawk" to set a preferred slogan. An attractive slogan could yield twice the results with half the effort.

If you want to cancel peddling, just click the "Cancel" button on the lower part of game screen.