<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>JavaScript</title>
  <script>
    function addClicks() {
      const list = document.querySelectorAll("section > p");
      for (let f = 0; f < list.length; f++) {
        const element = list[f];
        element.addEventListener("click", changecolor);
      }
    }
    function changecolor(event) {
      const element = event.target;
      element.style.backgroundColor = "#999999";
    }
    window.addEventListener("DOMContentLoaded", addClicks);
  </script>
</head>
<body>
  <section>
    <h1>Website</h1>
    <p>Message number 1</p>
    <p>Message number 2</p>
    <p>Message number 3</p>
  </section>
</body>
</html>