Every car is different. I suggest you buy the adapter for your car. It will click into your factory wiring harness and the loose wires will match those of the CD player. another option is to buy a checker. This is a pointy object with a wire on one side. You clip that wire onto any groung and the pointy part is used to touch wires. if the light turns on, that wire has power.
there are usually TWO of them. One goes to the 'always hot' lead and it is typically red or blue. The other goes to the 'only on when the key is turned' supply it will be red or blue (whatever is left over.
That make sure that when you turn the car off, the radio/player holds on to the information it needs to restarrt (location, volume, date time, etc..)
