If you'd like to setup an Overtime Alert, you can do this by visiting Settings --> Alerts & Reminders. Once on the Alerts & Reminders page, select +Add a New Alert.
When creating the alert, you'll need to enter the name. This name will be included in the alert message. You will also need to select the Type of alert - in this case you'll want to select "Overtime Alert" from the dropdown list as shown below:
You will then need to set the interval, you can select from Weekly or Daily, as well as enter how many hours and minutes an employee needs to work before the alert is triggered.
Lastly, you will need to decide who the alert will be sent to and what form it will be sent in. Don't forget to make sure to box next to Active is checked and that you assign employees to the alert.