Ive done alot of reading to get some basic applet creating knowledge,
however I have 2 questions: What happens when a shape goes off and you
cant see it anymore? Is it possible to destroy is when it leaves the
screen or do I need to reuse it?

And how would I create an array of rectangles?

I want to just go forward/ or backwards for what seems forever, run my
applet and you'll see what i mean.

My Code so far:

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class KeyboardTest extends Applet implements KeyListener {

int keyCode;
int x = 100;
int y = 100;
int width = 75;
int height = 100;

public void init() {
 addKeyListener(this);
}

public void paint(Graphics g) {
 g.drawRect (x-50,y-50,width+100,height+100);
 g.drawRect (x,y,width,height);
 g.drawRect (x+50,y+50,width-100,height-100);
}

public void keyPressed(KeyEvent e) {
 keyCode = e.getKeyCode();
  if(keyCode == 38)
  {
   x--;
   y--;
   width = width +2;
   height = height +2;
  }
  else if(keyCode == 40)
  {
   x++;
   y++;
   width = width -2;
   height = height -2;
  }
 repaint();
}

public void keyReleased(KeyEvent e) { }
public void keyTyped(KeyEvent e) { }

}