It’s really easy to override the header and footer in hobo. There are two ways to do this. I use both in aura-site.
First, look at the pages definition in rapid_pages.dryml. Everything with a param attribute can be redefined.
Note the main-nav element. By default, Hobo will magically generate a menu for you, based on your project. On aura-site, we override this in application.dryml to build our menus the way the admin wants.
Now you can also redefine the page as a whole. We do this in the aura theme to add a bit of css and javascript to the head of the html.
The easiest way to make a header or footer is to use this second method. Just use a <header:> to replace the header or <append-header:> to add to the end of it. Same deal with footer, just use the <footer:>, <append-footer:>, <prepend-footer:>.