If you are talking about ASP.NET - i.e. a website - then you don't want (and probably don't have access to) Windows task scheduler.
Instead, try setting up a task via your web hosts control panel:
How to Use Schedule Task in DotNetPanel to Execute a URL | Arvixe Blog[
^] explains how to do it for Arvixe hosted sites, but it's similar for others. This allows you to run an ASPX page at regular intervals, and it can do what you want it to there as part of your website structure.