Passing Files from a Web Service to a Client. Help!!

[User 1884058]

Hi I need to pass a file (any file xml,txt,.doc,.xls,.csv) from a webservice to a windows application. I need to get a file from a directory on the web server from the web service and pass it to the client(a windows application). The client will then work with that file and pass it back to the web service which should then store the file on the web server All help is appreciated