Customize CRE Loaded Template

To change background & header - server\templates\template\stylesheet.css

BODY {
/* background: #F5F7FC; */
background-image: url(images/bg.jpg);
color: #000000; margin: 0px;
}

HEADER{
header-image: url(images/header.jpg);
}
where images/ locate at server/templates/images/