This is a post that will be shown on all pages and in a Block. To do this just create a new post in your Home menu and set it to display on all pages and define a block for it and there you go.
Announcement
Starts: January 01 Ends: July 05
You can have announcements on your site too, just create a post as usually and at the Announcement Options select a start and end date and the announcement will show up on your site (if more they will be ordered by StartDate) and when EndDate is reached they will automatically dissapear from your site.
