Find Path of Any File

Hi everyone, I am trying to use a page with an Iframe as a web editor. I should be able to open any of my web pages, edit its contents, and then hit save. At least that's the theory. After editing a page, I ran into the problem of identifying the path of the page to save, using Server.MapPath().
I get the name of the file I opened in the Iframe using jQuery. Then I sent it to the MapPath() method but it points to the wrong parent folder. So suppose the name of the page I got from jQuery was Page1.html, MapPath() will show the path of Page1.html as 
"C:\\MyProject\\AuthorizedUsers\\Page1.html" instead of "C:\\MyProject\\Page1.html". How do I get Server.MapPath to point to any page correctly regardless of where it's located? Any help will be greatly appreciated, thanks in advance.