To add a student as Library Member, go to Library > Add student then select the Class and Section and then click on the Search button to display the student list. Now click on the + icon from the student's list, at the click of this icon a modal will open, here enter Library Card Number and then click on the Add button.
The added student will be shown in the green color row in the student list. To remove a student's membership click on the Surrender button present in the Action column.