This is outdated demo of HTML version (I’m taking it down now), the WordPress version does not support that – see official theme demo.
To do this in WordPress you’d have to put the banner directly in header.php, but so many people asks about it, that I think I’m going to add this functionality in the next update (not sure when exactly).
An update implementing this option is waiting to be pushed to official repository! I suggest just a little more patience 🙂 And please, whatever you do, DO NOT edit theme files directly. Child theme is the way to go!