<%@ Page Language="C#" MasterPageFile="~/Default.master" AutoEventWireup="true" CodeFile="Login.aspx.cs" Inherits="Default2" Title="First Website - Login" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
    <script runat="server">
        private void BTNLogin_OnClick(object sender, EventArgs e)
        {
            string message;
            if (TXTUsername.Text != "Admin" && TXTPassword.Text != "Admin")
            {
                message = "The details are incorrect";
            }
            else if (TXTUsername.Text == "Admin" && TXTPassword.Text == "Admin")
            {
                HttpCookie UserNameCookie = new HttpCookie("Username");
                UserNameCookie.Value = "Admin";
                UserNameCookie.Expires = DateTime.Now.AddYears(1);
                Response.Cookies.Add(UserNameCookie);
                HttpCookie PasswordCookie = new HttpCookie("Password");
                PasswordCookie.Value = "Admin";
                PasswordCookie.Expires = DateTime.Now.AddYears(1);
                Response.Cookies.Add(PasswordCookie);
            }
        }
    </script>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    <form>
    <table>
        <tr>
            <td>Username: </td>
            <td><asp:TextBox  ID="TXTUsername" runat="server" /></td>
        </tr>
        <tr>
            <td>Password: </td>
            <td><asp:TextBox ID="TXTPassword" TextMode="Password" runat="server" /></td>
        </tr>
        <tr>
            <td colspan="2"><asp:Button ID="BTNLogin" Text="Login" OnClick="BTNLogin_OnClick" runat="server" /> <input type="reset" value="Reset" /></td>
        </tr>
     </table>
     </form>
</asp:Content>

EnableEventValidation="true"