Um, you mean "how to upload .duc files", right...? Could you give more details please? It makes no sence...
Since the SAV and DUC formats aren't accepted as attachements in this forum, what about putting the file into a ZIP/RAR archive and uploading here?
You should convert your .duc file to a .sav
here first (choose "RAW Format" as the destination format) so any emulator will be able to read your save.