Using car's sound system on computer.

Hello everyone, I am planning to use car's speakers lying in my garage for years for using with my PC. This is how they look like, http://goo.gl/3V8aN9. I haven't had a look at them for a couple of years now. But as far as I remember there were just a single cable coming out of each one of them which I had to connect to the CD player. What do I have to do to power them externally connecting them to the computer using a 3.5 mm jack? Any guidance would be appreciated. I just want to get started, hopefully I will be able to figure out things after that.

Where does an Arduino come into this?

...R

I'm missing an amplifier in your set-up. The signal on the 3.5mm connectors of your PC probably isn't power full enough to hear music with the car engine on. Your CD-player probably had an amplifier integrated and you need one in your project as well.