How to browse the folders or files on server?

Question

Hi, Currently I am writting a web app use C# and ASP.net. The requirement is that: there is a button "browse..." on the web form, and if user click it, he will see the folders of the server after select one folder, the full path of this folder will be returned. There is no web contrl of showing the folder list. Does anyone know how to do it? It is really urgent! Thanks!