help installing after market stereo wiring problem

where does the aftermarket red wire goes 2? in a 1990 ls 4 door
and where does the yellow wire go 2?? i get display and everthin but no sound… please help. thx.

The instructions for the stereo should say what to connect the wires to. Usually one is always on (battery) and one is “on with ignition”. You can use a test light or a multimeter to determine which wires in your car can serve for this. Or this diagram might help:*+diagram