I'm not sure, but maybe I can help.
First for you to look up the12volt.com has great wiring diagrams.
Second, does your car have a striped and solid wire? Usually striped is positive and solid is negative.
Lastly, If you are doing all of the speakers it does not matter as long as you are consistent (same polarity) for all speakers. No harm will be done to radio or the speakers it would just make the speaker play out of phase which can severely effect sound quality.