很菜的问题,可是我不会

Question

网址是http://virscan.org/ 我想提交文件给它,然后返回结果,但是我不知道提交那些参数! procedure TForm1.Button1Click(Sender: TObject); 
var 
  IdHTTP1: tidhttp;   ResponseStream: TMemoryStream; 
  strme: Tstringstream; 
  str: string; 
  MultiPartFormDataStream: TMsMultiPartFormDataStream; 
begin 
  IdHTTP1 := tidhttp.create(nil); 
  MultiPartFormDataStream := TMsMultiPartFormDataStream.Create; 
  ResponseStream := TMemoryStream.Create; 
  IdHttp1.Request.ContentType := MultiPartFormDataStream.RequestContentType; // MultiPartFormDataStream.AddFormField('file', 'c:\a.exe'); 
// MultiPartFormDataStream.AddFormField('upload_button', '上  传'); 
  MultiPartFormDataStream.AddFile('file', 'c:\a.exe', 'multipart/form-data');   MultiPartFormDataStream.PrepareStreamForDispatch; 
  MultiPartFormDataStream.Position := 0; 
//调用idhttp的post方法，第一个参数是用于处理上载form的asp/php等等脚本，第三个是接收脚本执行完成后的返回内容) 
  IdHTTP1.Post('http://virscan.org/cgi-bin/upload.cgi?sid=36c26870a82dfc385d341551fb8bf720', MultiPartFormDataStream, ResponseStream); // ResponseStream.SaveToStream(strme); 
showmessage(StreamToText(ResponseStream)); 
  MultiPartFormDataStream.Free; 
  ResponseStream.Free; 
end;