Download the Jetpack plugin and use its Custom CSS functionality to hold your CSS modifications from now. Then enter within the Custom CSS section of the dashboard;
body {
background-color: #062d06;
background-image: url('http://360mrc.com/wp-content/uploads/2011/11/360Bgnd.png');
background-repeat: repeat;
background-position: top center;
background-attachment: scroll;
}