I was wondering if anyone knows how to add a left and right border to your site. My site width is 960px but I can't figure out how to add a 4px border to the left and right of the store.

You can do this by adding an image (or updating the current image if one is provided in your site theme) to the Left and Right Column Background Image (Tiled) settings in Layout >> Site Wide Color & Font Options >> Site Borders & Misc.

Thanks Mark. That's what I exactly did except I didn't have a right column so I made the right column 4px with background color.