display error msg if from date greater than to date greater

Question

I am posting the complete aspx code to show that this is my code the main thing in this code is from date and to date which is in bold and italic i should not allow the user to enter from date greater than to date also i should not allow from date and to date not greater than todays date i need to display label messages to the user if from date is greater than to date and from date and to date should not be greater than todays date

<pre><%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Home.aspx.cs" Inherits="Home1" %>

<%@ Register Namespace="AjaxControlToolkit" Assembly="AjaxControlToolkit" tagPrefix="ajax" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">

<script src="Scripts/jquery-1.4.1.min.js" type="text/javascript"></script>

<script src="Scripts/jquery.dynDateTime.min.js" type="text/javascript"></script>

<script src="Scripts/calendar-en.min.js" type="text/javascript"></script>

<link href="Styles/calendar-blue.css" rel="stylesheet" type="text/css" />

<script type="text/javascript">

$(document).ready(function () {

$("#<%= txtTAFromDate.ClientID %>").dynDateTime({

showsTime: true,

ifFormat: "%m/%d/%y %H:%M",

daFormat: "%l;%M %p, %e %m, %Y",

align: "BR",

electric: false,

singleClick: true,

displayArea: ".siblings('.dtcDisplayArea')",

button: ".next()"

});

$("#<%= txtTAToDate.ClientID %>").dynDateTime({

showsTime: true,

ifFormat: "%m/%d/%y %H:%M",

daFormat: "%l;%M %p, %e %m, %Y",

align: "BR",

electric: false,

singleClick: true,

displayArea: ".siblings('.dtcDisplayArea')",

button: ".next()"

});

});

</script>

<ajax:ToolkitScriptManager ID="scriptmanager1" runat="server">

</ajax:ToolkitScriptManager>

<div style="margin-left:10%;margin-top:03%;height:450px">

<ajax:TabContainer ID="TabContainer1" runat="server" CssClass="fancy fancy-green">

<ajax:TabPanel ID="tbpnluser" runat="server" >

<HeaderTemplate>Project wise details & Status </HeaderTemplate>

<ContentTemplate>

<asp:Panel ID="pnlPW" runat="server">

<h4><strong><center> Project wise details & Status </center></strong></h4>

<span>

Select ProjectName:<asp:DropDownList ID="ddlProject" runat="server" AutoPostBack="True" Width="183px" OnSelectedIndexChanged="ddlProject_SelectedIndexChanged"></asp:DropDownList>

</span>

(OR)<span>

Status:<asp:DropDownList ID="ddlStatus" runat="server" Visible="true" AutoPostBack="True" OnSelectedIndexChanged="ddlStatus_SelectedIndexChanged" >

</asp:DropDownList>

</span><span>

(OR) Domain:<asp:DropDownList ID="ddlDomain" runat="server" Visible="true" AutoPostBack="True" OnSelectedIndexChanged="ddlDomain_SelectedIndexChanged" ></asp:DropDownList>

</span>

<span style="float:right">

<asp:Button ID="Button1" runat="server" Text="Export" Visible="false"></asp:Button>

</span>

&nbsp;<div style="width:99%; height: 200px; overflow: auto">

<asp:GridView ID="grdPdetails" runat="server" EmptyDataText="No Records Available">

</asp:GridView>

</div>

</asp:Panel>

</ContentTemplate>

</ajax:TabPanel>

<ajax:TabPanel ID="tbpnlusrdetails" runat="server">

<HeaderTemplate>Team Activities</HeaderTemplate>

<ContentTemplate>

<asp:Panel ID="pnlAW" runat="server">

<h4><strong><center> Team Activities </center></strong></h4>

<div style="padding-left:100px">

<span>

ProjectName:<asp:DropDownList ID="ddlProjectNameTA" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddlProjectNameTA_SelectedIndexChanged"></asp:DropDownList> <%----%>

</span>

<span>

(OR) UserName:<asp:DropDownList ID="ddlUsers" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddlUsers_SelectedIndexChanged"></asp:DropDownList>

</span>

</div>

<br />

<b><b><div style="padding-left:100px">

<span>

(OR) From Date<asp:TextBox ID="txtTAFromDate" Width="113px" runat="server" ReadOnly="true" ></asp:TextBox> <img src="calendar.png" />

</span>

<span>

To Date<asp:TextBox ID="txtTAToDate" Width="113px" runat="server" ReadOnly="true" ></asp:TextBox> <img src="calendar.png" />

<asp:Button ID="btnGet" runat="server" Text="GET" OnClick="btnGet_Click"/></b>

</span>

</div></b> <asp:Label ID="lblErrmsgTA" runat="server" ForeColor="Red" Font-Bold="true"></asp:Label>

&nbsp;<div style="width:99%; height: 200px; overflow: auto">

<asp:GridView ID="gvTeamActiv" runat="server" EmptyDataText="No Records Available" >

</asp:GridView>

</div>

<asp:Button ID="Button3" runat="server" Text="Export" Visible="false"></asp:Button>

</asp:Panel>

</ContentTemplate>

</ajax:TabPanel>

</ajax:TabContainer>

</div>

</asp:Content>

</pre>