While looking at the details of an incident click 'Add Note'.
A modal will appear with a text box where the note should be typed in.
Once you are done, click Create Incident note and the Incident will be displayed with the new note added.
Hold the “Status” button to show an Incident history.
Click on the Incident you wish to reply to.
Press the “Update Notes” button.
Type in your note and press 'Send'.
Your note will now be displayed on the incident.