12V negative ground means exactly that.
negative, positive, ground? you ask?
Positive is the power side of the voltage.
negative and ground are both the same thing, these are the return line for the power side back to the battery which are linked to the chassis.
If you can, take a multimeter reading from a metal part of the players internal bits to each of the three connections, one should show a link and therefore is your negative return.
That leaves you with two terminals, one of which is the positive and is usually positioned on the opposite side to the negative to avoid accidents.
Assuming the audio signal inputs elsewhere, the third will be a low wattage remote feed.
Now once you've blown this unit up, go and buy one with instructions!
hope this helps.
ps, your english is better than some peoples on here !
