Learn CSS Flexbox by Building a Photo Gallery - Step 5

Tell us what’s happening:
Describe your issue in detail here.I dont div class know how to add please help

  **Your code so far**
/* file: index.html */
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Photo Gallery</title>
  <link rel="stylesheet" href="./styles.css">
</head>
<body> 
  <header class="header"><div class="gallery"><img><img><img><img><img><img><img><img><img></div>
   
    <h1>css flexbox photo gallery</h1>
        </header>
</body>
</html>
/* file: styles.css */
.header {div class:gallery;}
  **Your browser information:**

User Agent is: Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36

Challenge: Learn CSS Flexbox by Building a Photo Gallery - Step 5

Link to the challenge:

“Below your .header element…”

Adding something below an element means below the entire element. You have added everything inside the header element instead of below it.