Code and Output for header:

Code:

    <!DOCTYPE html>
    <html>
    <head>
      <title>HTML Example</title>
      <style>
      h1{color:red;}
      p{color:blue;}
      </style>
    </head>
    <body>
    <article>
    <header>
     <h1>App Genesis soft solutions pvt ltd</h1>
     <p>Hello World!</p>
     </header>
     <p>hii</p>
     </article>
    </body>
    </html>

Output:

App Genesis soft solutions pvt ltd

Hello World!

hii