Export HTML to Excel In window application c#.

 string str = @" <table>
                                    <thead>
                                      <tr>
                                        <th>Firstname</th>
                                        <th>Lastname</th>
                                        <th>Email</th>
                                      </tr>
                                    </thead>
                                    <tbody>
                                      <tr>
                                        <td>John</td>
                                        <td>Doe</td>
                                        <td>john@example.com</td>
                                      </tr>
                                      <tr>
                                        <td>Mary</td>
                                        <td>Moe</td>
                                        <td>mary@example.com</td>
                                      </tr>
                                      <tr>
                                        <td>July</td>
                                        <td>Dooley</td>
                                        <td>july@example.com</td>
                                      </tr>
                                    </tbody>
                                  </table>";
                File.WriteAllText(filename,str);