Transparent Background in Salient Theme

Hello! I am using the boxed layout of the Salient theme. The site has a background image in the main container div. The header and footer are covering the image so that not much of the picture is showing up. I would like to make the header and footer transparent so that more of the picture can be seen. Here is the site I am working on.http://parkin.silverfir.net/wordpress/ Could someone please tell me how to make the background transparent?
Thanks so much!