An FM transmitter accessory for a digital music player having a display screen uses a microprocessor to create image files that are transferred to the digital music player such that they are displayed on its screen. When a user input on the accessory is manipulated on the accessory to select a transmission frequency for the FM transmitter, the microcontroller generates a new image file that corresponds to the selected frequency and transfers the generated image file to the digital music player such that the selected frequency is displayed on the screen of the digital music player. In addition, by constantly generating new displays based upon user inputs, the accessory can display menus on the screen of the digital music player that can be manipulated by user to select between a number of displayed options.