VS 2010 access file on web server

Question

I have a 2010 C# web application that I am writing where I want to  be able to access some excel files that are located on a web server. I know if I want to access the files on my own workstation I would do the following:

file://localhost/c:/work/app or file:///c:/work/app.

However I do not know how to access the files on another web server. What syntax would I use?