Got difficulty with connecting spotify to my car!

[tomak8]

Hey, ive just bought a brand new ford fiesta edge 2012 plate car! Went to go get the usb lead to plug my iphone into the car and the car did not recognise the spotify app and could not play any music at all. So i thought no worry ill use the auxillary plug, but when i started playing music, it played but there was like a serious interference like a radio interference so i could barely even hear my music! So if theres anything that theres wrong with what im doing or i need something, could someone tell me!