How do you get a code if you don't have owners manuel?

How do you get a code if you don't have owners manuel?
I assume your talkin about check engine codes? 1994 and before is OBD1, which codes can be obtained through jumping certain pins on the plug located (usually) bottom left of the drivers side knee plate thing. (the panel under the steering column that you'd hit your knees on.) Your check engine light will flash your code "1,2,3...pause...1,2,3" (example) first series is your first number, second is your second number. 96 and after is obd2 which you have to use a scan tool for. autozone or similar place usually do this for free. I could help a little more if i had year make and model.