[Hilikus Funkin]

i hope everyone remembers me, i see alot of new people on here and i havnt been on the forums for a few months.

But anyways i have a 91 civic 4 door dx and i bought my stereo and speakers a while ago but one of my speakers never worked bc i think its hooked up wrong. Its my right rear speaker. Its hooked up in the back and all but i dont think its hooked up to the stereo. A guy from best buy told me that the wire that hooks up to the harness from the aftermarket stereo is a purple wire. But the problem is i dont know which wire to hook the purple wire to. and is there a neg and pos wire? Honestly i know nothing about stereos or anything but i would appreciate the help.