iPhone5s link to car radio

i have an iPhone5s, fully updated. I understand that I can play through my car radio music from my iPhone. I am a Jazz enthusiast and get JazzFM on my iPhone5 and I would like to play this radio music through my car radio, but I don't know how to set it up

To the best of my knowledge, there is no Jazz on the radio as such, therefor the iPhone is the only source

Any advice or instructions appreciated