OK so,
You click on add on 'New Booking Alert'

You add the Regarding to what Record that the alert is related to
You add Assignee's to who will see the alert on the schedule board.
Due Date is when you expect the task to be finished

The new Booking Alert will appear as an activity on the Regarding Record you specified

The Alert will appear on the schedule board for the Assignee's you specified

I found that Alerts tend to take a while to appear on the Schedule board. If you find that the alert is taking a long time then just wait while for it to appear.