how to send email in asp.net when the user enter the email in the textbox using c#

MailMessage mail = new MailMessage();
mail.To.Add("to_address1@something.com");
mail.To.Add("to_address2@something.com");
mail.From = new MailAddress("noreply@something.com");
mail.Subject = "Subject here";
mail.Body = "Body text here";

SmtpClient smtp = new SmtpClient();
smtp.Host = "smtp.something.com";
smtp.Credentials = new System.Net.NetworkCredential("UserName","Password");
smtp.Send(mail);