1) Choose your prefered market from the main page.
2) Enter your price (bid or ask) and amount you wish to buy or sell in selected currency.
3) After you click buy or sell your order will be listed in the order book.
4) As soon as your price gets a cross match your order will be completed.
5) When there are orders where the bid price is equal or higher than the lowest ask, those orders can be immediately fulfilled and will not be part of the open orders book.