This step is so easy you won't believe it.  Let the paint dry for a few minutes.  How long will depend on the room's temperature and level of humidity.  (Don't you hate it when directions say crap like that?)
Once the paint is the tiniest bit sticky, begin stabbing at it with your application brush.  Use a variety of motions so that you get all sorts of crazy nonsense patterns just as Mother Nature might produce when weathering metal over time.  Nature is random, so you should use random strokes, too.
Your final stroke should be to wipe a little more paint off the point of interest (the rose) so it really jumps!