One of the neat features that Genesis includes out of the box is the option to enter Headline and Intro Text for category archives. These, if present, will automatically appear above the list of Posts for that specific category page.
To enter Headline and Intro Text, edit a category and scroll down to Category Archive Settings section.
Archive Intro Text text area works in Text mode – meaning, paragraphs separated via enter/return key will get wrapped in p tags and HTML code gets rendered.