Thanks for the reply.
there are three steps :
1. upload a file from my machine ( client ) to server machine using CGI -> i am done with this part.
2. convert the uploaded file to the required format -> i am done with this part too.
3. Now the converted file is under some dir of server machine , now i want to get ( downlaod ) this file back to may local machine ( client ) -> i am stuck in this part.