You can add notes to accompany any of your tasks.
When you select a given task, simply tap on the "Note" tab to include comments.
Notes can be anything you feel is important for you or your care provider to know. For example, for a task asking you to rate your pain level on a scale from 1 to 10, you might feel you were at a 5 for the day on average but you were a 7 for a few hours following a workout. You can add that clarification in a Note.