body {
height: 100vh;
background: url(relative path or url in double quotes) | linear-gradient()
background-size: cover | contain | any unit value e.g. 1500px;
background-attachment: fixed | local | scroll;
background-position: x-offset(values:left,center,right) y-offset(values:top,center,bottom);
/* or single value for both x & y-offset */
background-repeat: repeat (enabled by default) | no-repeat;
/* some of them will only work provided height of the container */
/* That's pretty much it folks */
/* I can't cover details of each value. You'd have to search it */
}