how to send email with verification link when user completes his registration in asp.net c#

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Linq;
using System.Xml.Linq;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.SqlClient;
using System.Configuration;

public partial class Registration : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
     SqlConnection con = new SqlConnection(
     ConfigurationManager.ConnectionStrings["BMCConnectionString"].ConnectionString);

    // open the data connection.  
    con.Open();
}
protected void Button1_Click(object sender, EventArgs e)
{
     if (IsPostBack)
    {
        Response.Write("<script>alert('Thanking you .....Registration Successful')</script>");
        TextBoxDate.Text = DateTime.Now.ToString();

        SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["BMCConnectionString"].ConnectionString);

        con.Open();
        string insCmd = "insert into Registration(UserName, Password, RePassword, Email, FullName ,Date ,Month, Year, Gender, Area, Date1) values (@UserName, @Password, @RePassword, @Email, @FullName ,@Date ,@Month, @Year, @Gender, @Area, @Date1)";
        SqlCommand insertUser = new SqlCommand(insCmd, con);
        insertUser.Parameters.AddWithValue("@UserName", TextBoxUN.Text);
        insertUser.Parameters.AddWithValue("@Password", TextBoxPW.Text);
        insertUser.Parameters.AddWithValue("@RePassword", TextBoxRP.Text);
        insertUser.Parameters.AddWithValue("@Email", TextBoxEA.Text);
        insertUser.Parameters.AddWithValue("@FullName", TextBoxFN.Text);
        insertUser.Parameters.AddWithValue("@Date", DropDownListDate.SelectedItem.Text);
        insertUser.Parameters.AddWithValue("@Month", DropDownListMonth.SelectedItem.Text);
        insertUser.Parameters.AddWithValue("@Year", DropDownListYear.SelectedItem.Text);
        insertUser.Parameters.AddWithValue("@Gender", RadioButtonList1.SelectedItem.Text);
        insertUser.Parameters.AddWithValue("@Area", DropDownListArea.SelectedItem.Text);
        insertUser.Parameters.AddWithValue("@Date1", TextBoxDate.Text);
{
                //create the mail message
                MailMessage mail = new MailMessage();
                //set the addresses
                mail.From = new MailAddress("salvevishal9@gmail.com");
                mail.To.Add(TextBoxEA.Text);
                //set the content
                mail.Subject = "This is an email";
                mail.Body = "this is the body content of the email.";
                //send the message
                
                SmtpClient smtp = new SmtpClient("smtp.gmail.com");
                smtp.Port = 587;
                smtp.EnableSsl = true;
                smtp.Send(mail);

        try
        {
            insertUser.ExecuteNonQuery();
            con.Close();

        }
        catch (Exception er)
        {
            Response.Write(er);
        }
    }
}