Hi studio,
You can add background properties to the <body> tag in configurable.css (webassist/themes/whichever_theme_you_chose/css/configurable.css) at line 1:
body {
background-color: #354F68;
color: #C7C7C7;
font-family: Arial,Helvetica,sans-serif;
font-size: 11px;
}
The code above currently specifies a background color. If you wanted to add a background image, the properties would be (something like):
body {
background-color: #27394B;
background-image: url("../images/bg_image.jpg");
background-repeat: repeat-y;
background-position: center top;
color: #C7C7C7;
font-family: Arial,Helvetica,sans-serif;
font-size: 11px;
}
And yes, it is a great product.