w3schools background code example

Example 1: css background image

background-image: url("image.png");
background-position: center;
background-repeat: no-repeat;
background-size: cover;

Example 2: css change background color of page

/* Use the following code: */
html {background-color: #fefefe;} 
/* You can change the hexedecimal code to RGB, RGBA, name & more colors!*/

Example 3: how to change background color in css

body{
  background: lightblue;
}