Hey Mitch,
This is a bit beyond the scope of wyBuild. You can use server logs to get a count of number of times a file has been successfully transferred. Or, if you want to really complicate things, your "update site" could be a webpage which increases a counter and sends your file to your user (See limiting updates for an idea how to do this.). But this puts an unnecessary load on your server's CPU when server logs would give you all you need to know.