Adding header to div

This might seem elementary but I want to know how to add a header to a div.

For example, at the bottom of this page:
http://www.diverstories.com/circled-by-a-thresher/

in the beige box with the Sumome share buttons, I want to add a header.

Can I just hardcode that? is there a way to use ::before or ::after?

Thanks