There are several ways to use your iPod in your car.  The easiest way is to use a FM transmitter.  But the sound quality is very poor.  The second way is to use a cassette adapter if your car has a cassette player.  The sound is better but many new cars don’t have a cassette player.  The ultimate way is to connect your iPod directly to your car stereo.  Some new cars have line in and it is easy to connect your iPod.  But most of older cars don’t have line in.  So you need to install either an iPod friendly car stereo, or use CD changer or Neo iPod adapter.   The following video show you have to install a Neo iPod adapter.

For the instruction of how to install a iPod friendly car stereo read cnet instructions.

Related:

How to replace your ipod, iPhone battery

How to transfer music, video from iPod or iPhone to your computer

Convert DVD to iPod video