This document will guide you to post a sell order. Some important notes are included.
First, get into the exchange from the main menu, then hit on the "Post an order" button at the page heading. You'll get into the composer.
Once there, change the order type to "Sell" and pick up the coin you want to trade away:
Specify the amount you want to sell.
As you might notice, as soon as you type a number in the amount to sell, the table will be updated.
Once you decide the amount, you need to select which coins you want to take:
Since you're selling a coin, you don't need to have any of the coins you want to receive because the fee is charged over the coins you're selling, and the amount of coins you specify will be locked out.
Once your selection is done, you'll have to scroll down to see the forms being added.
On each coin you might want to set a price. Click on the icon near the price input box on each coin and a dialog will explain the price types:
Once you're happy with your order, just click on the big "Submit order" button at the bottom. The order will be saved and you'll be sent back to the listings page.
You can check all the orders you've created on "My orders". Learn more