Here are simple instructions for a simple samba file share on ubuntu 12.04 server.
All commands are ran as root. If you are not root use sudo before the commands.
1. Install samba.
apt-get install samba
2. nano /etc/samba/smb.conf
[share]
comment = share
path = /share
browsable = yes
guest ok = no
read only = no
available = yes
public = no
writable = yes
valid users = user
3. (the share is called share. make sure you have a user called user on your server or replace with a valid user on your server)
save and restart samba.
4. restart smbd
restart nmbd
5. chmod -R 0775 share (You can use filezilla over sftp if you want)
https://help.ubuntu.com/12.04/serverguide/samba-fileserver.html
http://ubuntuserverhelp.com/basic-samba-configuration/