You can edit the same post over and over to make new specials, or you can make new posts each time.  This area can show as many posts as you want (but 1-3 is ideal), and people can click on it to see related posts.

You can also schedule posts in advance for daily specials.

To make posts appear here, choose “Daily Specials” from the categories list on the right when you make a new post.

There is also a way to make posts expire if you are interested.