I have tried to change the background img and color but doesn't seem to work with the light version of Photography.
I found the following in your Appearance → Custom Design → CSS editor:
body {
background:url('http://whitelineninteriors.files.wordpress.com/2012/05/zigzagbackground2.jpg') repeat top left;
}
In order to override an existing background image already set by the theme or by the Appearance → Background or Theme Options pages, you need to make the new rule you ad more specific. One way to do that is to use "!important". Here is an example:
body {
background:url('http://whitelineninteriors.files.wordpress.com/2012/05/zigzagbackground2.jpg') repeat top left !important;
}