This can be done by navigating to the Officials tab on the left-hand side and then select the "Add Official" button.
You may then either search by FAN, details or create a new FAN if the person does not have one.
You will need the persons Date of Birth before you can select search. The matching individual will be displayed.
You must select the add to club box next to the name. Then select from the role drop-down, choose the role you wish to assign to the person and select a start date. Once every has been filled in, you should be able to click OK and the new Discipline Officer role will be added.