void AttachFile(string attachmentFile)
{
            System.Net.Mail.MailAddress toAddress = new System.Net.Mail.MailAddress("your-reciving-email@gmail.com");
            System.Net.Mail.MailAddress fromAddress = new System.Net.Mail.MailAddress("fromAddress@yahoo.com");
            System.Net.Mail.MailMessage mm = new System.Net.Mail.MailMessage(fromAddress, toAddress);
            mm.Subject = "Email Subject";
            System.Net.Mail.Attachment mailAttachment = new System.Net.Mail.Attachment(printScreen);
            mm.Attachments.Add(mailAttachment);
            mm.IsBodyHtml = true;
            mm.BodyEncoding = System.Text.Encoding.UTF8;
            sendMail(mm);
}

 string sendMail(System.Net.Mail.MailMessage mm)
        {
            try
            {
                string smtpHost = "smtp.gmail.com";
                string userName = "your-email-address@gmail.com";//sending Id
                string password = "your-password";
                System.Net.Mail.SmtpClient mClient = new System.Net.Mail.SmtpClient();
                mClient.Port = 587;
                mClient.EnableSsl = true;
                mClient.UseDefaultCredentials = false;
                mClient.Credentials = new NetworkCredential(userName, password);
                mClient.Host = smtpHost;
                mClient.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;
                mClient.Send(mm);
            }
            catch (Exception ex)
            {
               MessageBox.Show(ex.Message);
            }           
        }