can some one tell me how to use the steptronic transmission can I change the D to S/M in any speed or change back?

You really can't damage anything by using Sport, Manual, or Drive. If you tell it to shift into a gear that would damage the engine or transmission, the computer just politely says "no" and refuses to do what you told it. Yes, you can shift it into D, S, or M at any speed, and neutral if necessary for whatever reason - anything but reverse or park, really, and they require brake pedal application. However if you are constantly (i.e shifting your automatic manually like every 5-10 seconds for no reason), it will wear things out quicker. Very unlikely that anything will break immediately though.