You must be able to see the directory, eg.
where nnn.nnn.nnn.nnn is your external IP address and /images (or whatever) is your Web directory.
If you want to use internal IP addresses on your lan, I have an enhancement to do that (it "pulls" images, rather than "push" them):
You just need to replace the original asp/htm files with the revised ones. Also, this enhancement has a new XML configuration file that will hide the server parameters in the browser by setting a flag on (instructions are in that file). The updated article explains how this enhancement works.