Is not the background for the widgets under Style Widgets>Widget Containers? This is the code that is there.
Code:
font-family: tahoma, arial, sans-serif; vertical-align: top; font-size: .9em; line-height: 1.4; padding: 5px 5px 5px 5px; margin-bottom: 5px; margin-left: 5px; background: url("/hoffbrau/wp-content/themes/atahualpa.3.7.9/atahualpa/images/paper.jpg") repeat scroll center top;