Small web app

I need a web app which, put simply, will update a text file from an HTML page. The text file is made up of 365 entries, one for each day of the year. It's formatted like this: #01-01Message here #02-01Message here #03-01Message here #04-01Message here #05-01Message here ..etc? Where 00-00 is the date (day-month), and the text which follows is the 'message'. The html page should have a javascript-type calendar, which the user can click on any date of the year and retrieve, and update, the 'message' which follows the date. When the user updates the text, this text needs to be written directly/immediately to the .txt file. Needs to be able to run on IIS and update the text file stored on a locally mapped network drive (j:\files\[login to view URL]) Please message me if you have any questions.