Shoutbox

Could you describe how to set up sharing folders please?
The problem being that I want to do this through windows, and even though I have sharing enabled the folders don't show up in my network places, and the computer is inaccesible, sometimes giving me the 'you might not have permission error' and sometimes the 'unspecified logon type' error, or sometimes it refuses to believe the other computer is there.

Yet when I connect a LAN cable between two laptops at school, I can access the other persons files.