How do I show an announcement across the top of my site?

In your site's CMS, open Menu Layouts, then Header, then the Announcement Bar tab. Turn the bar on, write a short message (a new season, a live show, a sale), and optionally add a link so people can act on it. The message shows in a band across the very top of every page until you turn it off.

To count down to a deadline, set Show a countdown to Yes and pick the date and time, in your site's time zone. The countdown follows the message, and the bar stops showing when it reaches zero. Set Show a countdown to No to hide it without losing the date you typed.