You're sound system should have an Auxiliary port (or jack). Get yourself an AUX (Auxiliary) cable. It will probably be a 3.5mm male to male jack. Plug one end in to your iPhone and the other into the sound system. Set the function on the sound system to AUX. You should be gold. And if the music isn't coming through and you've got it cranked right up, try turning the music up on you phone.
