To use your MP3 player with your car radio, you have several options: 1) Connect the unit to the car radio by means of USB. If the car radio has a USB port, you can use it to connect the MP3 player to the radio. The player will display ?connected to the PC? on the screen, and the car radio will take over functions such as play and pause. 2) Connect the unit to the line-in of the car radio. Connect the unit to the line-in of the car radio, and select the correct source mode on the car radio. Use the MP3 player to play, pause, and navigate through the menus, for example. 3) Use FM Transmitter AY4601 Connect the FM transmitter to the headphone jack of the MP3 player, and manually tune in to the correct frequency, as selected on the FM transmitter, on the car radio.