[Samba] administrative shares

[Luca Ferrari]

Hi all,
I cannot find a good description of how to use the windows administrative 
shares. Since I'd like to mount them from a Linux box, using samba, to 
perform backup of the user client, I'd like to know how can I access them. In 
particular, in a computer where I've got a single user, without password, 
what are the share credentials? And how can I set permissions for such share?
Any good document?

Thanks,
Luca