by loren_d_c » Fri Apr 03, 2015 9:56 am
In the Navigation menu, select one of your existing Footer Page Links, then click Add and make a new link. This will be a sub of the one you selected before clicking add, and will display underneath it in a column format. So you may want to make your 1st level navigation items just headers for your columns instead of links (choose the 'No URL (a title maybe)' option when adding or editing the link) and then have all the sub-items be the links in that column.
Note that the Left, Footer, and Right Page Links are limited to two levels like this, but the 'Menu', which is generally used horizontally across the top, can have more sub-levels, allowing for more specific category/subcategory/subsubcategory/etc drill-down in fly-out menus.
-Loren