New to Java

Hi, I have to do the following :
(1)Write a class called Student with the following private member variables:
name [String]
id [long]
marks [float]

(2)It must have the following methods:

Methods to set name, set ID, and set marks
Eg: public void setName(String newName) { … }

Methods getName, getID, getMarks, eg:
public long getID() {
return id;
}
(3)Note that the set and get methods do not normally display messages on screen. However, setMarks should display an error if the marks are not in the range 0 - 100, and set the member variable marks to 0.

(4)To test the Student class, write a Test Class that creates a Student object and sets its name, ID and marks. The program should then display the student's name and marks in a message box.

Its parts (3) and (4) Im having trouble with. Im not sure is part 3 correct and cant check it if I dont know what to do for part 4

import javax.swing.JOptionPane;
public class Student {
	/**
	 * OBP
	 */

	private String name;  // Student's name.
	private long ID;  // Unique ID number for this student.
	private float marks;   // Grade

	private static int nextUniqueID = 0;
	// keep track of next available unique ID number
	
	Student(String newName) 
	{
		// Names Student, assigns the student a unique ID number
		name = newName;
		nextUniqueID++;
		ID = nextUniqueID;
	}

	public String getName() 
	{
		return name;
	}

	public long getID() 
	{
		return ID;
	}

	public float getMarks() 
	{  
		return marks;
	}

	public void setName(String newName) 
	{
		name = newName;
	}
	
	public void setID(long newID) 
	{
		ID = newID;
	}
	
	public void setMarks(float newMarks)
	{
		if (newMarks >=0 && newMarks <=100) 
		{
		marks = newMarks;
		}
		else
		{
			JOptionPane.showMessageDialog(null, "Marks must be >=0 and <=100");
			marks=0;
		}
	}
}

Im still new to this so be gentle :P
Thanks