Car Won't Start

What is your question?

The car won't start. The electronics light up when the ignition is turned and there is a sound like it is trying to start but it never gets there. It can't be the starter because we have had it replaced twice within the past year and after both replacements the car still seemed to not start as readily as when we first got it. Also before the car gave out there started to be a rough idle. Does anyone know what it could be? My guess is there is some bad wiring somewhere or the ECM is bad. How and where do I check for the problems and how do I fix them?