The footer of the webpage is always located at the very bottom, regardless of whether you are on a site, a category or a portal. The footer is site specific, and will be displayed on all categories and portals that belong to the that site.
To configure the footer, you use the same layout tool as for the other layouts, Pages and Layouts editor. The background color and font color are set in the Theme Editor.
The content of the footer is added from a Site home, and the content of the footer will be the same for the entire site