The dark grey area at the top will be the header graphic. The lighter grey area underneath will act as banners to promote indie games, videos, etc. The white area is the main container, which will have a few vertical columns containing the majority of the pages content. Finally, the footer (light grey area at the bottom) will be for your personal account settings, updates, alerts, etc.
Time to start cutting up the main container into columns and get some data pulled into the page.