Halogen contains 5 Extra Content Areas to expand your design choices and options. The Extra Content Areas are limited to using the Extra Content Stack with Stacks 2 and therefore can only be used on pages built using Stacks 2. You can download the Extra Content stack for free under Extra Content Stacks Plugin at the following link: http://extracontent.info/downloads/
Please note that the Extra Content Areas begin with Extra Content #4 and end in Extra Content #8. Do not use any other Extra Content Areas as they are being utilized for other functions related to the theme. The Built-In Style Options of the theme include the ability to utilize your own custom background image, or choose between 12 background textures, or any solid color.