Need help powering a sub bass processor kit i bought.

I have built the kit, making sure I have all polarities correct and making sure not to burn IC's (I used sockets for these).
The kit requires +15V, -15V and 0V. How do I supply this?
Can such a circuit be run in my car? Could I run it from my computer?
I am only a beginner to electronics, but audio circuitry interests me. Any help appreciated.

You should mention how much current it needs, but unless it has a power amp inside, I'll assume not too much. You can buy a +15/-15 power supply from many sources. 0 is just the ground reference for that design. It might work from your auto's 12V (you would get less dynamic range), but you need a switching converter to generate the -12V.

You could also use a 9-10Vrms transformer to create a +/- 15V supply.