Adding content to UberMenu is just like adding content to any other WordPress 3 menu via Appearance > Menus. Start by checking out the Content Creation basics article. The remainder of the articles explain how to add each type of content to the menu, including normal menu items, descriptions, images, widgets, content overrides, and shortcodes.
Heads up!
This archived doc is for an old version of UberMenu.
For the current documentation, please visit the UberMenu 3 Knowledgebase