Send Mail with Attachment Files Using Asp.net

using System.Net.Mail;

SmtpClient client = new SmtpClient();

            client.Port = 587;

            client.Host = "smtp.gmail.com";

            client.EnableSsl = true;

            client.Timeout = 10000;

            client.DeliveryMethod = SmtpDeliveryMethod.Network;

            client.UseDefaultCredentials = false;

            client.Credentials = new System.Net.NetworkCredential("xyz@gmail.com", "Password");

            MailMessage mm = new MailMessage();

            mm.Subject = "Sending Mail Using Asp.net";

            mm.Body = "Hi, \n\n\Mail Sent Successfully \n\n\n --\n -- \nBest Regards\n"

                + "\n\n-----------------------------------------------------------------------\nThis is a system-generated e-mail, please don't reply to this message.";

            mm.Attachments.Add(new Attachment(File));

            mm.From = new MailAddress("xyz@gmail.com");

            mm.To.Add("xyz@gmail.com");             

            mm.CC.Add("xyz@gmail.com");

            client.Send(mm);