First you must click click on "Wallets" at the top of the page.
Then click on accounts as shown below
Then once you have clicked that you will have the following dropdown box
You must ensure you have ticked the ETN box. You will now be able to see ETN as a wallet on the left of your page.
Click on that and then you will see the following.
You then want to send your ETN to the first address with the payment ID being the second address.