You do need to know HTML and CSS to design a new landing page template or edit existing templates. I mean, you can just use a blank template an layer elements on to it in Design Studio, but to create a new custom template, knowledge of code is needed.
For your immediate problem, just pull up that code window, copy/paste everything into a Notepad txt file and save it as a backup. Now, on the screen with the code displayed, Ctrl+F, enter 2011 and Search, change the 2011 to 2013 and save. That should at least update your copyright date. Preview one of t he affected pages to ensure that it worked, then approve any active landing pages using that template.