Download the net.hires.debug.Stats class and copy it in your application source code structure.
add a new object to the main sprite object:
addChild( new Stats() );
If you prefer different colors you can add some custom parameters:
addChild( new Stats( { bg: 0xffffff, fps: 0xff0000, ms: 0x00ff00, mem: 0x0000ff, memmax: 0x0000aa } ) )