trouble with permissions

I want to be able to access files on 3 networked pcs, all running xp,
from a laptop. The three are wired through a Belkin router (and
through that to my ntl cable modem), and the laptop is wirelessly
connected via a switch.

All works fine - all pcs can see the others, all can access the
internet etc.

But I can't figure out the permissions procedure. What on earth is an
'object'? - and how do I configure the permissions dialogue box with
them??

TIA