How to use "gid" permission

[Massimo Alonzo <massimo a flashnet it>]

Hi,

I tried to give my user the permission of writing on a vfat partition
(applying gid) but I think I made a mess ...... and obviously it doesn't
work.


Can you explain me, in details,  howto? 


This is my configuration:

user name is: host_user
shared vfat: /dev/hda2



What book,or guide or tutorial,  can I read to find infos related to
system administration?

Thanks for your help

Massimo