You would need to add a hook and you could register a widget to be placed in that area if you wanted to use a widget. Otherwise, using a hook in your functions.php to place content there would work fine.
You can use that plugin if you want. I prefer to use the functions.php through FTP, so if I ever have an error in my code, (a typo, etc) I can easily undo or correct the mistake if the site goes down.