Sending an email not from gmail account

Question

I have purchased a domain with registration , so I have now mail account of my own company , i wrote a function to send an email below is the code for email sending 

protected void SendEmail(object sender, EventArgs e)

{

using (MailMessage mm = new MailMessage(txtEmail.Text, txtTo.Text))

{

mm.Subject = txtSubject.Text;

mm.Body = txtBody.Text;

if (fuAttachment.HasFile)

{

string FileName = Path.GetFileName(fuAttachment.PostedFile.FileName);

mm.Attachments.Add(new Attachment(fuAttachment.PostedFile.InputStream, FileName));

}

mm.IsBodyHtml = false;

SmtpClient smtp = new SmtpClient();

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

smtp.EnableSsl = true;

NetworkCredential NetworkCred = new NetworkCredential(txtEmail.Text, txtPassword.Text);

smtp.UseDefaultCredentials = true;

smtp.Credentials = NetworkCred;

smtp.Port = 587;

smtp.Send(mm);

ClientScript.RegisterStartupScript(GetType(), "alert", "alert('Email sent.');", true);

}

}

Now as my email is [email protected] as it is not a gmail account so instead of this line  smtp.Host = "smtp.gmail.com"; what should i write