<html>
<body>
<h1>New topic</h1>

<form action="<%= url_for(:action => "create_topic") %>" method="post">
  <p>
    Title:<br>
    <input type="text" name="topic[title]">
  </p>

  <p>
    Body:<br>
    <textarea name="topic[body]" style="width: 200px; height: 200px"></textarea>
  </p>

  <p>
    <input type="submit" value="Create topic">
  </p>
</form>

</body>
</html>