I wrote this code first as a class to get information of a student and calculate average
 * This program shows a database of students in a school.
 * It gathers information as name, classes, grades, and calculates average.
 * @author Luis Gerardo Fierro
import javax.swing.JOptionPane;
public class StudentReport 
	public static  void main(String[]args)
		String name;			//name of the student
		String schoolName;		//name of the school
		String schoolGrade;		//grade in school
		int numOfGrades;		//number of grades or number of classes
		double grades;			//grades received
		double average;			//average of the grades
		double total=0;			//total of the grades 
		String trash;			//to convert string to double
		//ask user for Name, grade, school
		//ask user to enter number of grades
		trash=JOptionPane.showInputDialog("Number of grades:");             
		numOfGrades=Integer.parseInt(trash);				              		                                                                  // All in one
		//calculate average
		//get the grades added together in order to calculate the average
		for (int i = 1; i <=numOfGrades; i++) 
			trash=JOptionPane.showInputDialog("Test " + i + " : " );
		//display window showing information
		JOptionPane.showMessageDialog(null, "School name: " + schoolName + "\n"			
						+ "Student: "+ name + " \n "                                    
				                                + "School grade: " + schoolGrade + "\n"	                        
						+ "Average: " + average + ".");	                         	    

Now I ma doing a program that tests that class. I will be using GUI, but because I know that I need to add something in
the first class in order to be able to call it in the demo program. The thing is that I don't know what to add the in the first code
in order to bring that information to calculate gpa, also I have no clue how to convert decimal average into gpa (0-4 scale).

import javax.swing.JOptionPane;
import javax.swing.*;
import java.awt.event.*;
This program test the StudentReport class to display in 
a GUI format average and calculates the gpa based on that information.
public class ReportGenerator extends JFrame{
private JLabel mesLab;	//to present the title of the program
private JButton start;		//button to go to the next window, start the program
private JButton calc;		//calculate button
private JPanel panel;		//panel to hold components
private final int WINDOW_WIDTH= ; 	//
private final int WINDOW_HEIGHT= ;	//
private double getGpa;	//calcualte gpa
private double getAvg; 	//receive average results from the StudentReport class
private StudentReport calculator;	//to the class reference
ReportGenerator constructor
public ReportGenerator ( )
    //set title
	setTitle("Student Report");
    //set the title size of window
    //what happens when close button clicked
    //create the buttons
	start = new JButton("Start");
	calc = new JButton("Calculate");
    //event listener with the buttons
start.addActionListener(new ButtonListener( ) );
calc.addActionListener(new ButtonListener( ) );
//create a panel to add the buttons
	panel = new JPanel( );
//add panel to the content pane
//display window
	setVisible (true);
inner class  that handles the reaction 
of the buttoons
private class StartListener implements ActionListener
	public void actionPerformed(ActionEvent e)
		 //get the action command
            String  actionCommand = e.getActionCommand();

The code is still unfinished and I know it is way out of working conditions but that is the main idea.
My idea is that the GUI should prompt a first window with the title of the program and a button saying start to use the program
Then it should prompt a new window to add enter the user's information, and finally at the bottom of the second window
the button calculate, it would display a third and last window showing the information entered by the user, average and gpa.
I kind of got an idea of what I should do but still I'm not completely in track because my first class works by itself.