Hello,
This background is for the image only. If you want to add background image to sj travel ii, please open templates/sj_travel2/css/template.css file, find
body{
background:#fff;
font-family:Arial, Helvetica, sans-serif;
color: #666666;
line-height:20px;
}
Here you can add background image. Please refer this guide
davidwalsh.name/css-fixed-position-background-image to add background image
Thanks