@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_menu_01);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_menu_01, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);

  }
}

<ImageButton
    android:id="@+id/your_id"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>

ImageButton myButton = (ImageButton) findViewById(R.id.the_button_you_created_on_the_layout.xml_file);

myButton.setOnClickListener(new View.OnClickListner(){
    // When the button is pressed/clicked, it will run the code below
    @Override
    public void onClick(){
        // Intent is what you use to start another activity
        Intent intent = new Intent(this, YourActivity.class);
        startActivity(intent);
    }
});

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_menu_01);
    ImageButton button = (ImageButton) findViewById(R.id.my_button);
    final Context context = this;
    button.setOnClickListener(new View.OnClickListner(){
        @Override
        public void onClick(View v){
            Intent intent = new Intent(context, NewActivity.class);
            startActivity(intent);
        }
    });
}