Thank you.. the messages are working.

the only thing is .. i want the the app posts the picture with a message to the users timeline.. does anyone know how to do this? alot of these apps are doing this.. Here is my app:

its on facebook too. i dont know it because im new to facebook apps :/

example: if a user opens the app a random picture appears. lets say picture 2.
and this picture should be postet to the users timeline so that his friends sees it and uses the app too..