Type in <ul> to start this unordered list.

<html>
<body>
  Top 3 Comets
  <ul>
   <li>Halley’s Comet</li>
   <li>Shoemaker Levy-9</li>
   <li>Hyakutake</li>
  </ul>
</body>
</html>]]>

Make sure to type <ul>.