try as follows...
RelativeLayout layout = new RelativeLayout(this);
RelativeLayout.LayoutParams lprams = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.MATCH_PARENT,
RelativeLayout.LayoutParams.MATCH_PARENT);
lprams.setMargins(5,5,5,5);
layout.setLayoutParams(lprams);
layout.setBackgroundResource(R.drawable.step_background);