file storage

on it says I can point to a different directory if I don't want to store my images on the server. I am not a php person. Is this the right place to put my web address: (do I replace $_webDir with my directory ([filename].jpg)

property Omeka_Storage_Adapter_Filesystem::$_webDir
protected string

Web-accesible path that corresponds to $_localDir.

Can someone give me the proper syntax? Thanks