Machine B will have to offer them (server), and
machine A will have to access them (client)
Makarand Dodmis has described the process for the server, but this may be specific to the Windows version. Can you tell us what versions the Server and the Client are running?
Once the server is sharing, we need to tell the client to connect and then this will appear as another disk as you look on your client.
Have a look at
this search for more help.
Robin