how to send email

ma cs file code is
 
 protected void btn_send_Click(object sender, EventArgs e)    {   SendMail("tayal_tushar006@yahoo.co.in", "tushartayalster@gmail.com", "Request For Information", txt_name.Text);
    }
    public void SendMail(string from, string to, string subject, string body)    {        string body_txt = string.Empty;        System.Net.Mail.MailAddress mail = new MailAddress("tushartayalster@gmail.com");        SmtpClient MailObj = new SmtpClient();        System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage();        MailAddress fromAddress = new MailAddress(from);        message.From = fromAddress;        message.To.Add(mail.Address);        message.Subject = su ...