Listen to iPhone in cars with no iPhone adapter?

My car doesn't have a USB port to plug my iPhone in to listen to music. I don't have a cassette player, so I can't buy a iPhone/cassette player adapter. I'm wanting something that will allow me to listen to music from my iPhone in my car through the car charger/cigarette lighter or any other way that would work. I've tried to look up ones to buy, but I'm just not positive what to type in to look. Everything that comes up is nothing at all what I'm needing!

If its new like my dads car, look for a hole in the radio area the size for headphones. It's called an auxiliary cable and they're $6 at Walmart, the look like the end of headphones in both ends. If its like my moms car and just has a CD player there's nothing you can do but put in a new system

Look up the Jupiter jack it works perfectly for listening to music on your phone and answering calls