Ubunturial have posted a small guide to setup NAS on 6.06.
Read it here
This tutorial is extrememly easy to carry out and takes less than 5 minutes.
First you will need to install the following 2 pieces of software; Samba & SMB. There is a good chance that Samba has already been installed but for the same of things it wont hurt to check by using the apt-get command.