Quote:
tell me how to copy files from one folder to another folder in my asp .net web application
I think this is where you should rethink your solution. ASP.Net is a hosted runtime and as such it has abstraction layers between itself and the OS, which owns the filesystem.
Therefore you should not use a web application to control the file system.
There are several suggestions in this thread already of how to use Windows service technology and/ or filesystem watcher class instances to control the filesystem which you can use from csharp, but it should not execute from asp.net you should begin to forget that idea ;)
Otherwise the execution context of your application pool beeing in use by your website will need elevated rights which you shouldn't grant to something that can be executed from outside the box itself in such an accessible way like the HTTP(s) protocol.