create E-mail service in asp.net

private void btnSend_Click(object sender, System.EventArgs e)  {
MailMessage msg = new MailMessage();
msg.To = this.txtTo.Text;
msg.Subject = this.txtSubject.Text;
msg.Body = this.txtBody.Text;
msg.From = "info@Builder.com";
SmtpMail.SmtpServer = "localhost";
SmtpMail.Send(msg);
}