Check out example codes for "how to insert background image in html". It will help you in understanding the concepts better.

Code Example 1

<html>
<body>

<h2>Background Image</h2>

<div style="background-image: url('img_girl.jpg');">

Code Example 2

<!DOCTYPE HTML>
<html lang=us>
  <meta charset=UTF-8>
  //the following code within the style tags is CSS.
<style>
  /*this is a body tag. After specifying 
  that we want to affect the whole body,
  we add {}, and write the background color
  we want to change it to. */
  body{background:rgb(255,0,0);
  }
  /* this is a class, which we have named green. we add {}, then
  write the background color we want.*/
  .green{background:green}
   /* this is an id, which we have named blue. we add {}, then
  write the background color we want.*/
  #blue{background:blue}
</style>

<body>
This background is red.
  // you must make sure to note that when you add a background to
  a paragraph, you must add a class or id, name it, then style it 
  as seen above.  with tags HTML already recognizes, however, you 
  don't have to do anything more than shown above.
  <p class="green">
  This background is green.</p>
  <p id="blue">This background is blue.</p>

</body>

</style>
</html>

Code Example 3

body{
background-color: url('url from web');
}

Code Example 4

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

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