ASP - when Register Send Mail

Design Master-Page and create Asp.Net pages with the use of created master- page to demonstrate Navigation controls. Also design a page to store registration data to database and inform candidate for confirmation through email.

ASPX file 

<Code>

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

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    name:<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
    <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ErroDisplay="Dynamic" ControlToVrMessage="enter name" ControlToValidate="TextBox1">*</asp:RequiredFieldValidator>
    <br>
    Email:<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
    <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ErrorMessage="enter Email" Display="Dynamic" ControlToValidate="TextBox2">*</asp:RequiredFieldValidator>
    <asp:RegularExpressionValidator ID="RegularExpressionValidator6" runat="server" ErrorMessage="enter valid Email" ControlToValidate="TextBox2" ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"></asp:RegularExpressionValidator>
    <br>
    Address:<asp:TextBox ID="TextBox3" runat="server" TextMode="MultiLine"></asp:TextBox>
    <asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" ErrorMessage="Enter Address" Display="Dynamic" ControlToValidate="TextBox3">*</asp:RequiredFieldValidator>
    <br>
    Password:<asp:TextBox ID="TextBox4" runat="server" TextMode="Password"></asp:TextBox>
    <asp:RequiredFieldValidator ID="RequiredFieldValidator4" runat="server" ErrorMessage="enter same Password" ControlToValidate="TextBox4" Display="Dynamic">*</asp:RequiredFieldValidator>
   
    <br>
    same Password:<asp:TextBox ID="TextBox5" runat="server" TextMode="Password"></asp:TextBox>
    <asp:RequiredFieldValidator ID="RequiredFieldValidator5" runat="server" ErrorMessage="enter same Password" ControlToValidate="TextBox5" Display="Dynamic">*</asp:RequiredFieldValidator>
    <asp:CompareValidator ID="CompareValidator1" runat="server" ErrorMessage="Compare pass" Type="String" Operator="Equal" Display="Dynamic" ControlToValidate="TextBox5" ControlToCompare="TextBox4"></asp:CompareValidator>
    <br>
    <asp:Button ID="Button1" runat="server" Text="submit" OnClick="Button1_Click" />
</asp:Content></code>

ASPX.CS File

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;
using System.Net.Mail;

public partial class resister : System.Web.UI.Page
{
    SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=D:\asp.net\tuto6\App_Data\librarys.mdf;Integrated Security=True");
    SqlCommand cmd;
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    public void sendmail()
    {
        MailMessage mail = new MailMessage();
        mail.To.Add(TextBox2.Text);
        mail.From = new MailAddress("username");
        string body = "welcome to learn for codes";
        mail.Body = body;
        SmtpClient smtp = new SmtpClient();
        smtp.Host = "smtp.gmail.com";
        smtp.Port = 587;
        smtp.UseDefaultCredentials = false;
        smtp.Credentials = new System.Net.NetworkCredential("username","password");
        smtp.EnableSsl = true;
        smtp.Send(mail);
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        SqlCommand cmd = new SqlCommand("insert into student values(@name,@email,@add,@pass)",con);
        cmd.Parameters.AddWithValue("@name",TextBox1.Text);
        cmd.Parameters.AddWithValue("@email", TextBox2.Text);
        cmd.Parameters.AddWithValue("@add", TextBox3.Text);
        cmd.Parameters.AddWithValue("@pass", TextBox4.Text);
        con.Open();
        cmd.ExecuteNonQuery();
        int a = 1;
        con.Close();
        if (a == 1)
        {
            sendmail();
            Response.Write("successfull registerd");
        }
       
    }
}