well, if you using Steam client u should move cursor on the top 'COMMUNITY' and see 'Market' point, click on it and MArket open. After this on the top of new page you'll see big green button "SELL ON MARKET" or smth like this :) Choose item, check price diagram like on stock market (XD) and set price. Profit :)
Market operations history like sell/buy you can check at this page too :)
Write me/add me if you have any question about selling (or I toll not enough clear because of my grammar)) but I'm not a pro, yesterday were my first saling, "total sell" of all the garbage xD
I saw guys make money on craft/sale usefull items like Treasure key etc :)

yeah, i dont know how to do it and saw you had listed some so you must know :) thanks

Hey man :)Do you asked me how to sell your Mann Co on market? :)