TPL Files and customizing your pages

I need to add a hyperlink to an area of my site. The element comprises a gradient based area with an image over the right hand side. I need this whole area to be a link. But you can’t add a hyperlink with CSS and I don’t want to do it via a module based solution. I want to edit the Drupal files themselves (properly subthemed, or at least submoduled) so that I can understand the product better and be able to make whatever changes that I want to in the future. So, I am going to get the old Quality environment going and test it out there. when I have a procedure in place, I’ll write it up.