There are two ways to run scheduled tasks in Umbraco:
TaskScheduler provides a good interface for setting tasks in the Umbraco backend. You can schedule tasks to be completed at specific times, and you can set repetition. It can also send emails when performing tasks.
Adding tasks to umbracoSettings.configmight be easier. The following is an example:
<scheduledTasks>
<task log="true" alias="test60" interval="60" url="http://localhost/umbraco/test.aspx"/>
</scheduledTasks>