setting permissions

[john <rohiteshsingh@softhome.net>]

	hi there

i m new to linux and well after using debian on my system and on a test small 
network at home,

found out it was very good

a quick question is,

apart from doing things graphically

we can use the command line to do what we need

m stuck on the aspect where, considering setup of a linux box with  shared 
folders but setting permissions for t he folders

like writing to it or ..writing to files and folders under it 

need to know what command i can use so i can write to all files and folders 
under any folder which is shared on a network

thanks again

john