How to get input in array of class in java?

I am new to java and this is our first assignment but i am unclear right now that why didnt our teacher passes a array of class object to the Add Student method instead he created array of object as private and just passed the name of the array.How can i add data of students now

  public class StudentManagement {
    private Student students [] ;
    private int CAPACITY ;
    private int CURRENT_POSITION;
    public StudentManagement(){
        CAPACITY = 3;
        CURRENT_POSITION = 0;
        students = new Student[CAPACITY];
    }

    public void addStudent(Student student){


    }