(JS DOM) creating new elements in divs

So, I was trying to make a web app which acts like bot which uses a the textarea element as input. While referring to the JS DOM docs provided by W3Schools, I saw that my code was not working. I’m also new to JS DOM, so please forgive me if i’m the stupidest person you’ve ever met. (which i probably am)

Code: 

<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>replit</title>
  <link href="https://bot.valueyu.repl.co/style.css" rel="stylesheet" type="text/css" />
  <link rel="stylesheet" href="https://www.w3schools.com/w3css/4/w3.css">
  <script src="script.js"></script>
</head>

<script>
  function reply() {
    const rplyBox = document.getElementById('rplyBox')
    const input = document.getElementById('msgBox').value;
    if (input === "help") {
      const embed = document.createElement("div");
      embed.classList.add("w3-round-xxlarge", "w3-margin-top", "w3-margin-bottom", "w3-margin-right", "w3-margin-left")
      const title = document.createElement("h1")
      title.createTextNode("Help");
      const desc = document.createElement("h3")
      desc.createTextNode("All of my commands!");
      const field1 = document.createElement("h6")
      field1.createTextNode("e");
      embed.appendChild(title);
      embed.appendChild(desc);
      embed.appendChild(field1);
      rplyBox.appendChild(embed);
    }
  }
</script>

<body style="background-image: url('https://bot.valueyu.repl.co/bg.mp4'); background-repeat: no-repeat; background-size: cover;">
  <div class="main">
    <t>bot.valueyu</t>
    <p>bot.valueyu is a bot made by Aarav Saini/Valueyu. For commmands type "<span
        class="w3-text-white">help</span>".</p>
    <hr>
    <textarea class="w3-round-large w3-bar" id="msgBox"></textarea>
    <br>
    <br>
    <br>
    <button id="submit" onClick="reply()" class="w3-round-xxlarge w3-button">Send</button>
    <hr>
    <div class="w3-bar w3-white w3-round-large" id="rplyBox">

    </div>
  </div>
</body>

</html>

Any help would be much appreciated.