There are a couple of different options for notes; you can choose which suites you best.

Clicking on the eye-shaped icon lets you choose which things display on your Jobsheet.
 
Schedule notes are accessed in the Housekeeping tab of a booking
Click Edit beside the schedule you want the note on (likely Arrival or Departure) and save notes under "Schedule Notes"
 
 
Room notes are added in the Notes tab of a booking. Notes here will show up on all housekeeping jobs for this booking.
Booking notes refers to the notes field in the column on the right of bookings. Many properties use this for non-housekeeping notes, so it's not always the best choice.