Yes you can add ETF to your Watchlist or Portfolio. Usually the ETF does not rate good so you cannot add them via the rating section however, you can search for them.

On the top right of the screen you have a search box that will bring you to the stock's details.




From there you can use the link on the right (below the chart) to add it to your Watchlist. 

 



Then from the Watchlist you can create an order.