You will need to open the Services applet in the Administrative Tools of the Windows Control Center.  Locate the FoxWeb service and open its properties.  In the Log On tab select "This account" and specify a userid and password for a user that has access to the remote resource.

 

In order to refer to the remote file in your script you must use UNC notation (\\ServerName\Share\Path\FileName).  To verify that everything is correct, log into the server as the FoxWeb service user and try to open the file interactively in VFP, using the same UNC path as what you used in your script.