Attendance is a separate school tool: it lists scheduled lessons and marks student statuses during class. It's not a tab within the course editor.
To mark attendance, open "Education" → "Attendance" (or click the tile on the dashboard). The page displays upcoming lessons for today and lessons completed over the past month. Click "Mark Attendance" for a lesson. A modal will open with a list of students (by section for streams) and their statuses. The attendance report is available in the "Reports" section of your profile.
The first "present" mark can immediately start the payroll calculation if the rates have already been set.