I usually advocate removing the security during the config process. The reason being is you are then permitted to concentrate on the working of the connections and not wonder if Security is disallowing the connection.
So to that end I will in the file /usr/local/etc/smb.conf set the line
Once your configuration of the smb.conf is completed and working You can choose another security level
security = user
security = domain
security = server
I have a Quick Samba config How to that I have set up and use. It is basic easy to understand and I wil post it in Tips/Tricks to give you a quick start.