Creacion nuevas actividades codigo

------CLASE PRINCIPAL*********

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {

    private Button bSalir;
   
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
       
        bSalir =(Button) findViewById(R.id.Button04);

        bSalir.setOnClickListener(new OnClickListener() {

                   public void onClick(View view) {

                       finish();

                  }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
   
    public void lanzarAcercaDe(View view){

          Intent i = new Intent(this, Aercade.class);

                startActivity(i);

        }
   }

----CLASE ACERCADE**********
import android.app.Activity;

import android.os.Bundle;

public class Aercade extends MainActivity {

         /** Called when the activity is first created. */

         @Override public void onCreate(Bundle savedInstanceState) {

             super.onCreate(savedInstanceState);

             setContentView(R.layout.aercade);


     }
}