how to make a background panel in html code example

Example 1: background color using css

/* To apply color to background you have to use 'background-color' property and value of property is color name. */
html,body {
  background-color: blue;
}

Example 2: background css

/* Color (Example: red): */
html,body {
  background-color: red;
}

/* Image (Example: your.picture): */
html,body {
  background-image: url("your.picture");
}