I am not sure I understand the question correctly.
Would you like to know *how* to configure CIFS shares on your filer? That's a simple one: "cifs shares -add <shareName> <path> [ -comment <description> ]" on the command line.
Or, if you use FilerView go to "CIFS > Shares > Add" and click away.
If you are using an AD tree give permissions and distribute the share, may it be LAN or WAN.
Though, whether sharing over WAN is feasible or not depends very much on speed, traffic and load of the line, and also on the size of transmitted data.