How to add attachment to SMTP email?

I can send an email.  How do I add an attachment?  Usually is an MS-Word
doc, sometimes txt file.

I have this working, but don't know what to do next:

procedure TMyEMail.SendMail(vFromAddress, vFromName, vToAddress,
                            vSubject, vBodyText, vLogFile, vAttachment:
string);
begin
  IdMessage1.From.Address := vFromAddress;
  IdMessage1.From.Name := vFromName;
  IdMessage1.Recipients.EMailAddresses := vToAddress;
  IdMessage1.Subject := vSubject;
  IdMessage1.Body.Clear;
  IdMessage1.Body.Add(vBodyText);
  try
    try
      SMTP.Connect;
      SMTP.Send(IdMessage1);
      except on E:Exception do
        Application.messagebox(Pchar(E.Message), 'ERROR: ' , 1);
    end;
    if vLogFile > ''
      then WriteToLog(vFromAddress, vToAddress, vSubject, vLogFile);
  finally
    if SMTP.Connected
      then SMTP.Disconnect;
  end;
end;