In windows nntp server,
You can also post and configure nntp for private group.
To do like, Go to Internet Services Manager in Administrative group. Right click server select new->NNTP virtual server
Type the Description ->next->type the tcp port number->next->type the storage location
->next->in select storage medium, select remote share->next->select path to store news and give the private news group address user name and password->finish.