Asp.net in Html Form

<table style="width: 100%;">
                                  <tr>
                                      <td class="auto-style1">
                                          <asp:Label ID="Label6" runat="server" Text="Name"></asp:Label></td>
                                      <td>
                                          <asp:TextBox ID="TextBox2" runat="server" AutoPostBack="True" OnTextChanged="textBoxValidate"></asp:TextBox>
                                          <asp:Label ID="Label7" runat="server" Text="Label" ForeColor="Red" Visible="False"></asp:Label>
                                      </td>
                                  </tr>
                                  <tr>
                                      <td class="auto-style1">
                                          <asp:Label ID="Label2" runat="server" Text="Email Id"></asp:Label></td>
                                      <td>
                                          <asp:TextBox ID="TextBox3" runat="server" AutoPostBack="True" OnTextChanged="textBoxValidate"></asp:TextBox>
                                          <asp:Label ID="Label8" runat="server" Text="Label" ForeColor="Red" Visible="False"></asp:Label>
                                      </td>
                                  </tr>
                                  <tr>
                                      <td class="auto-style1">
                                          <asp:Label ID="Label3" runat="server" Text="Subject"></asp:Label></td>
                                      <td>
                                          <asp:TextBox ID="TextBox4" runat="server" AutoPostBack="True" OnTextChanged="textBoxValidate"></asp:TextBox>
                                          <asp:Label ID="Label9" runat="server" Text="Label" ForeColor="Red" Visible="False"></asp:Label>
                                      </td>
                                  </tr>
                                  <tr>
                                      <td class="auto-style1">
                                          <asp:Label ID="Label4" runat="server" Text="Your Question"></asp:Label></td>
                                      <td>
                                          <asp:TextBox ID="TextBox5" runat="server" TextMode="MultiLine" AutoPostBack="True" OnTextChanged="textBoxValidate"></asp:TextBox>
                                          <asp:Label ID="Label10" runat="server" Text="Label" ForeColor="Red" Visible="False"></asp:Label>
                                      </td>
                                  </tr>
                                  <tr>
                                      <td class="auto-style1">
                                          <asp:Label ID="Label5" runat="server" Text=""></asp:Label>
                                      </td>
                                      <td>
                                          <asp:Button ID="Button1" runat="server" Text="Submit" OnClick="SendEnquiry" /></td>
                                  </tr>
                              </table>