Check out example codes for "how to make a picture your background on 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

<!-- Code by Scratchy -->
<!-- Twitter: @S_cratchy-->

<head>
  <style>
    body {
      background-image: url(https://wallup.net/wp-content/uploads/2019/09/110394-cats-grey-kittens-fluffy-fat-grass-animals-cat-kitten-baby-cute-748x468.jpg) 
    }
  </style>
  
  <body>
    You have set the background image!
    
    
    
  </body>

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