Nothing is automatic. Nor will you have to enter names every week.
You will have your form open to a Class and week as I mentioned before. It will be blank, you will click a 'Add Enrollment' button at the top, VBA will fire that creates a record in the Attendance table for every person enrolled in that class, each record will be dated with the date the form is open to, the sub-form of that form which is based on the Attendance table will refresh to show those new records at that time you can then mark who was Present/Absent.
You will not have to manually enter names every week, but you will have to manually set up Enrollment in a class once and you will have to manually click a button to add the appropriate records to the Attendance table for every class/week you want to take attendance for.