I Cant understand why this messege come--------->

java.lang.NoSuchMethodError: main Exception in thread "main" .

I know it expecting main() method but as i m building an applet which does not contain main method rather contain init() method.So what will i do??My code is s follow --->

import java.applet.*;

import java.awt.*;

public class Ballbewegung1 extends Applet implements Runnable

{

// Initialisierung der Variablen

int x_pos = 10;     // x - Position des Balles
int y_pos = 100;    // y - Position des Balles
int radius = 20;    // Radius des Balles

public void init()
{
    setBackground (Color.blue);
}

public void start ()
{
    // Schaffen eines neuen Threads, in dem das Spiel l?uft
    Thread th = new Thread (this);
    // Starten des Threads
    th.start ();
}

public void stop()
{

}

public void destroy()
{

}

public void run ()
{
    // Erniedrigen der ThreadPriority um zeichnen zu erleichtern
    Thread.currentThread().setPriority(Thread.MIN_PRIORITY);

    // Solange true ist l?uft der Thread weiter
    while (true)
    {
        // Ver?ndern der x- Koordinate
        x_pos ++;

        // Neuzeichnen des Applets
        repaint();

        try
        {
            // Stoppen des Threads f?r in Klammern angegebene Millisekunden
            Thread.sleep (20);
        }
        catch (InterruptedException ex)
        {
            // do nothing
        }

        // Zur?cksetzen der ThreadPriority auf Maximalwert
        Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
    }
}


public void paint (Graphics g)
{
    g.setColor  (Color.red);

    g.fillOval (x_pos - radius, y_pos - radius, 2 * radius, 2 * radius);
}

}

And I dont know how to use code tag.so plz someone ans.