To mark student attendance, go to Attendance > Student Attendance then select Class, Section and Attendance Date and then click on Search button. The list of student will be shown in the below of the page.
Here select Attendance (Present, Late, Absent, Half day) for the students, you can also select Mark as Holiday (National and Sunday holiday) and then click on the SaveAttendance button.
To edit student attendance, click on the Attendance (Present, Late, Absent, Half day) present in the Student list then click on the Save Attendance button.