how to give numbers to table content in html code example

Example: table html tages

<table>
  <tr> <!-- This is the first row -->
    <th>This is the heading</th>
    <th>Next heading to the right</th>
  </tr>
  <tr> <!-- This is the second row -->
    <td>This is where the table data goes</td>
    <td>This is the second columns data</td>
  </tr>
</table>