1) Plug car Mp3 transmitter into car 2) Plug audio frequency connector of car Mp3 transmitter into earphone jack of your MP3 or other audio sources 3) Open your MP3 and tune the volume up rather range (about 2/3 of the whole volume range) 4) Set up FM channel as same as frequency of car MP3 transmitter, then car radio will search music station automatically 5) Turn the volume of car radio till satisfaction