97635 Web Form post to .txt file

I need a simple web based webform that acts as a script that will allow the user to edit their existing ads in a .txt file. The normal way to do this is to edit [login to view URL] (via ftp) and save it back to the server. I need a script that can open this .txt file in the browser see the existing ads, edit and save the ads easily all via a webform post method.