I have 2 questions, How to get codes from the ECM unit and how to check the check engine light?

You need a code scanner. Stores like Pep Boys and Autozone will usually pull codes for free. You may also find some repair shops that will do it for free.

Yes, I know that but what i don't know is how to do this in a 1992 car. I need to know how to locate the module I will be adapting the unit to and what adapters I may need to use as this is an older vehicle. Thank you as I realized my question was rather vague when i head your reply. Please excuse my vagueness. Thank you, Priscilla

There is no adaptation required. You need an OBDII code scanner. The connector, unless it's been modified, is generic/universal.

Ok, thank you for that information but it was my understanding that those were good for cars that are 1995 or newer. So, my question is will it still fit a 1992? Also, I still need to know how do i check the check engine light? As I do realize I sent a two part question and perhaps should have used more clarity. Or, will I need to send another request for that answer?

The check engine light indicates that the computer has stored a fault code.
I was wrong. You're looking at an OBDI. The scantool should have any adapters you need. I initially bought one of the cheap ones and it came with everything I needed. You may have to tell whoever it is what kind of car it is. Check through the yellow pages for a shop that will do all of that for free. I live in a very rural area and there are 3 shops that provide that service for free.