Edit your /etc/fstab file (vi or nano) and add the following line:
For Cifs Share without password protection
//server/share /media/usb cifs guest,_netdev 0 0
For Password protected shares:
//192.168.1.100/share /media/usb cifs username=USNERNAME,password=PASSWORD,_netdev 0 0
You can use hostnames or IPs. I recommend using IPs because you avoid DNS problems.
You must create the folder /media/usb in advance. After you edited your fstab file use "mount -a" or restart your box.