Speaker wiring

I have a 2000 Impala LS and would like to know if anyone knows what speaker wiring goes connected to which speaker connector. My front harness was removed by my cousin on both sides because he wanted to surprise me by putting in new speakers. (He cut them out then tossed them away). On the drivers side the wires are 1 yellow- 1 grey. . .on the other side they are 1 light green- 1 blue. The speakers have one fat pin and one thin one. I want to make sure I get it right so they don't cancel each other out bass wise! What ever happened to just plain
pos+neg wiring being the same on both sides? HELP ME PLEASE.