[Sanjip Shah]

@andrella You can add a background image/color from Appearance->Background. Now one thing you could do is if you wan the same image/color to appear in the header or footer part you can add the following custom css in Appearance->Theme Options->Design Options->Custom CSS.

#branding, #colophon {
    background: none;
    border: none;
    -moz-box-shadow: none;
    -webkit-box-shadow: none;
    box-shadow: none;
}