Place buttons at bottom of screen with background in BlackBerry

I have been working to get a background image in my application and also arrange four buttons at the bottom of the screen to the image. Below I show the code which I have used to achieve it.

    HorizontalFieldManager manager = new HorizontalFieldManager();    

    manager.add(new ButtonField("1", FIELD_BOTTOM));
    manager.add(new ButtonField("2", FIELD_BOTTOM));
    manager.add(new ButtonField("3", FIELD_BOTTOM));
    manager.add(new ButtonField("4", FIELD_BOTTOM));

    mWidth = Display.getWidth();
    mHeight = Display.getHeight();
    final Bitmap backgroundBitmap = Bitmap.getBitmapResource("intro.png");
    HorizontalFieldManager BackGroundImage = new HorizontalFieldManager(HorizontalFieldManager.USE_ALL_WIDTH |HorizontalFieldManager.USE_ALL_HEIGHT)
    {

        //Override the paint method to draw the background image.
        public void paint(Graphics graphics)
        {
            //Draw the background image and then call super.paint
            //to paint the rest of the screen.
            graphics.drawBitmap(0, 0, mWidth, mHeight,backgroundBitmap, 0, 0);
            super.paint(graphics);
        }
    };

    BackGroundImage.add(manager);
    add(BackGroundImage);

The thing is that now I am not able to place the buttons at the bottom of the screen if I put a Field_BOTTOM is the horizontalFieldManager.

You can do like this, in your HorizontalFieldManager set its parameter as FIELD_BOTTOM

HorizontalFieldManager BackGroundImage = new HorizontalFieldManager(HorizontalFieldManager.FIELD_BOTTOM)

then add your buttons directly to this HorizontalFieldManager and then use setStatus(Field status) MainScreen method i.e.

this.setStatus(BackGroundImage);