Java Programming

Hello Everyone! I'm new to java. I have an important assignment, and I would really really appreciate if someone helps me even a little.

I have to draw some balls (shapes) moving to the screen.

But I have a problem, I cannot even draw shapes.
I use the following code but it doesnt recognizes the first import. (though I am a little confused about Jframe (whether should I use it or not), Swing, AWT, I dont know very well whats their differences and what are they about.

And there is no main function in here, should I implement one?? And please, if you know a good tutorial or some links that can help me draw shapes, I will be very thankful.

import java.awt.*;
import java.applet.*;
public class DrawExample extends Applet 
{
    Font bigFont;
     Color redColor;
     Color weirdColor;
     Color bgColor;

     public void init() 
     {
          bigFont = new Font("Arial",Font.BOLD,16);

          redColor = Color.red;

          weirdColor = new Color(60,60,122);

          bgColor = Color.blue;

      setBackground(bgColor);

     }

     public void stop()
     {
     }

     public void paint(Graphics g) 
     {

      g.setFont(bigFont);
      g.drawString("Shapes and Colors",80,20);
      g.setColor(redColor);
      g.drawRect(100,100,100,100);

      g.fillRect(110,110,80,80);

      g.setColor(weirdColor);

      g.fillArc(120,120,60,60,0,360);

      g.setColor(Color.yellow);

       g.drawLine(140,140,160,160);

     g.setColor(Color.black);

     }

}

Regards.
Edi