(thread: https://help.ubuntu.com/community/How%20to%20Create%20a%20Network%20Share%20Via%20Samba%20Via%20CLI%20(Command-line%20interface/Linux%20Terminal)%20-%20Uncomplicated,%20Simple%20and%20Brief%20Way!)

sudo apt-get update
sudo apt-get install samba
sudo smbpasswd -a <user_name>
# backup 
sudo cp /etc/samba/smb.conf ~
sudo vim /etc/samba/smb.conf

Add this at the end of file (shortcut G):

[<folder_name>]
path = <full_path_to_shared_folder>
valid users = <user_name>
read only = no

# restart to take effect
sudo service smbd restart