Web Page Link to file on remote server

Thanks for your time in advance!
My client has a database with pictures in a field. The picture path & file name are shared with the web page in order to click on the picture for viewing. We wish to keep the pics on the clients computer for editing purposes.
I want the web page to be able to link to these pics. I have shared the wwwroot folder with guest user through IIS. I have a configured a port forward (80) to that computer.
I was able to remote connect to another computer from the host computer of the pics and link to it ok. I assume since I was logged on to that machine that it may have inherited the user name & password as I was able to connect to the pics. I can't seem to connect to those pics now though when I am offsite and not logged into that network.
Example http://100.100.100.100/wwwroot/Final_2/4022.420.1044_lg.jpg (not actual IP address). Also tried other variations including http://100.100.100.100/Final_2/4022.420.1044_lg.jpg

I've searched for ways to include a user name and password in the link but cannot find one, if in fact I have to log in to see the pics. I was assuming since I have the folder shared it would allow me to view the pics from outside the LAN. Any thoughts or comments will be appreciated.

Thanks Again,
Brian.