Thank yo ufor your answers.
I don't want to buy anything, because I don't have any money^^. I don't have any job I'm still to school.
But, the MP3 hacking is interesting me. I'd like to do it with mine, wich is 4 go. But the jack connector is dead. I removed it and now I have 4 connecting on the motherboard. How can I connect a speaker to that? Because a speaker only has 2 connecting?
Then, to connect it and control it with the Arduino board, it looks easy.
The output form your player will be stereo, left and right, get some headphones and plug them into jack you have removed, you can then see how the left and right speakers on the headphones are connected.
Its usually just left, right and common connected to a Stereo jack.http://en.wikipedia.org/wiki/Phone_connector_%28audio%29#Tip-ring-sleeve_terminology