MODEL POP UP

 <style type="text/css">
        .modalBackground
        {
            background-color: Gray;
            filter: alpha(opacity=80);
            z-index: 10000;
        }
    </style>

<asp:Button ID="btnShowPopup" runat="server" Style="display: none" />
    <cc1:ModalPopupExtender ID="ModalPopupExtender1" runat="server" TargetControlID="btnShowPopup"
        PopupControlID="pnlpopup" CancelControlID="btnCancel" BackgroundCssClass="modalBackground">
    </cc1:ModalPopupExtender>
    <asp:Panel ID="pnlpopup" runat="server" BackColor="White" Height="100px" Width="450px"
        Style="display: none">
        <table width="100%" style="border: Solid 2px #D55500; width: 100%; height: 100%;
            font-family: Arial; font-size: 12px" cellpadding="0" cellspacing="0">
            <tr>
                <td>
                    GatePass
                </td>
                <td>
                    <asp:TextBox ID="txtGatePass" runat="server"></asp:TextBox>
                </td>
                <td>
                    VichalPass
                </td>
                <td>
                    <asp:TextBox ID="txtVichalNo" runat="server"></asp:TextBox>
                </td>
            </tr>
            <tr>
                <td>
                    Arrivel Time
                </td>
                <td>
                    <asp:TextBox ID="txtArrtime" runat="server"></asp:TextBox>
             
                </td>
                <td>
                    Remarks
                </td>
                <td>
                    <asp:TextBox ID="txtre" runat="server"></asp:TextBox>
                </td>
            </tr>
            <tr>
                <td colspan="4">
                    <center>
                        <asp:Button ID="btnUpdate" runat="server" CommandName="Update" Text="Ok" />
                        &nbsp;
                        <asp:Button ID="btnCancel" runat="server" Text="Cancel" />
                    </center>
                </td>
            </tr>
        </table>
    </asp:Panel>

<asp:LinkButton ID="LinkButton1" runat="server" onclick="LinkButton1_Click">Challan No.</asp:LinkButton>
                      protected void LinkButton1_Click(object sender, EventArgs e)
    {
        this.ModalPopupExtender1.Show();
    }