background-image: url('your image location'); code example

Example 1: background image syntax in css if it is in folder

/* The first method using an image on your server */
background: url('img/someimage.jpg');

/* The second method using an image hosted on another server */
background: url('http://www.someimage.com/someimage.jpg');

/* A third method that allows the site to determine protocol instead of explicitly defining it */
background: url('//www.someimage.com/someimage.jpg');

Example 2: CSS adding background image from file

/* The first method using an image on your server */
background: url('img/someimage.jpg');

/* The second method using an image hosted on another server */
background: url('http://www.someimage.com/someimage.jpg');

/* A third method that allows the site to determine protocol instead of explicitly defining it */
background: url('//www.someimage.com/someimage.jpg');