The today window gathers items that you have entered elsewhere as scheduled actions and lists them together in one place. Here you can quickly see if you have medications, measurements or activities that you need to complete today.
It's a quick way to make sure that you haven't skipped anything today. Click the check box under the "Completed" column when you have done the task.
Make sure to enter notes for side effects or other observations that might be useful for your doctor on your next visit.