This is a small and fast how to guide to enable sharing through sabma in Ubuntu 11.04.
sudo apt-get install smbfs
to install smb packages if you already ahven't.
Then create a password for the user whose folder you wish to share. In our case it the the "shareuser" user, so that we share his home directory and throw files locally.
Create a samba password for that user
sudo smbpasswd -a shareuser
Then add some lines to the smb.conf file
sudo nano /etc/samba/smb.conf
Add those lines
comment = shareuser Private Files
path = /home/shareuser
valid users = shareuser
public = no
writable = yes
Restart samba service and your done.
sudo restart smbd && nmbd
Make sure that your firewall is not blocking connections (check this for a firewall guide) and you are done.