how to create a JFrame in java

import javax.swing.JFrame;
import java.awt.Rectangle;
import javax.swing.JComponent;
import java.awt.Graphics2D;
import java.awt.Graphics;
import java.awt.Color;

public class ChrismasTree {
    public static void main(String[] args) {
        JFrame window = new JFrame();
        window.setTitle("Christmas Tree");
        window.setSize(800, 1000);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setVisible(true);
        DrawingComponent DC = new DrawingComponent();
        window.add(DC);
    }
}

class DrawingComponent extends JComponent{
    public void paint(Graphics graph0){
        Graphics2D graph = (Graphics2D) graph0;

        graph.setColor(Color.LIGHT_GRAY);
        graph.draw(new Rectangle(0, 710, 70, 60));

        graph.setColor(Color.BLUE);
        graph.draw(new Rectangle(70, 600, 50, 100));

        graph.setColor(Color.BLACK);
    }
}