Settings > Link Lists > "Alert" or "Alert - Off"

This link list is used for the site wide alert.  The link list should be labeled "Alert" to turn on and contain a single link entry.  The name is the heading field, the description field is for the alert text.  If a url and the button text are used, a button will display below the description.

The alert will display as an overlay to the billboard/hero are of the page.  The billboard area must be in use to display (header image, video or rotator).