a) Please upload the background image in wp-content/themes/vertoh/images (png or jpeg format is better).
b) Open wp-content/themes/vertoh/css/layout.css. Add the following style,
section, #site-footer, #tile_contact{ background:url(../images/UE-seamless-wallpaper-grey.png)!important ;} // replace with your image name
c)Update the file.