Sounds like you have a stereo radio, which means you will need a 3 speaker dash, a crossover box and the correct harness.
Otherwise , if your car is a single dash speaker, your car originally had an AM radio and the green/black speaker wires from the radio would plug directly into the speaker itsself.
If you have green black amd purple speaker wires ,that's stereo,and you will not be able to hook that radio to a single dash speaker .
The green and purple are both pos + speakers and both channels share the black as ground .

Greg