The Notes module shows a list of the notes that have been entered into the register for a given day.
This can be found at via Register > Notes
Once you click the Notes button, the screen below will be presented.
Choose the day from the calendar, the time period and the Year and/or Form. Then the list of students will be presented. 
From the screen above, you can choose to enter an attendance code if 'Not registered' is displayed.
Choose the code from the drop-down list and write any notes in the box next to this.
There is the option to click the Register ALL Students button to marl all pupils present for the chosen date.
Notes can be viewed and edited for current pupils but this feature is not available for Off-Roll students.
If you need to look at register notes over a specific date range you can go to Reporting > Custom Report:
Select New Report, put the date range you require on the left side of the screen, and under Attendance on the right side choose Attendance Notes:
Any Attendance Note recorded in this period will appear in the Attendance Notes column, although the exact date of the note is not recorded (you will need to go to the student profile, Attendance Tab, to check this).
In this area you can filter for a particular Note type, e.g. Chicken Pox (enter the search term in the search box beneath the title cell) to get totals for a particular note category.