How to Send Free SMS using C#?[With Source Code]

CODE:
using System.Net;
using System.Net.Mail;
string to, from, mess, pass;
            MailMessage message = new MailMessage();
            to = (txtPhone.Text).ToString();
            from = (txtGmail.Text).ToString();
            mess = (txtMessage.Text).ToString();
            pass = (txtPass.Text).ToString();
            message.To.Add(to);
            message.From = new MailAddress(from);
            message.Body = mess;
            SmtpClient smtp = new SmtpClient("smtp.gmail.com");
            smtp.EnableSsl = true;
            smtp.Port = 587;
            smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
            smtp.Credentials = new NetworkCredential(from, pass);
            try
            {
                smtp.Send(message);
                MessageBox.Show("send successfully", "message", MessageBoxButtons.OK, MessageBoxIcon.Information);

            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.Message);

            }
        }

for all procedure you must watch video: