does anyone use samba need some help

Hi, I now see my ubuntu machine from the windows machines.
What do I have to edit to be able to log on to the ubuntu computer from the 
windows machine.
I thought it used the same user name and password I use to log on when gnome 
starts.
However this isn't the case because it doesn't work.
If a new user name and password has to be set up,
has anyone had experience doing this.
Mike.
X-Antivirus: avast! (VPS 000735-1, 04/21/2007), Outbound message
X-Antivirus-Status: Clean