Change "about" page background image

Love the theme so far, but I’m a joomla user so this is all new to me.

http://www.abovereno.com – I’m using the default “about” page as the home page, how in the world do I change the background images??? I cannot find that area whatsoever

Additionally what would I need to do to have it be a video (as shown in some of the demo pages, an auto loading “lower quality” video as the background)