Transfer Credits

Hey, i really need some guidance. please help me out.
I did my first year of medical school from a different college. i am filling up my online form for step1. i added the medical school and mentioned the duration but i am stuck on what are no of credits earned. i added three courses anatomy physiology and biochemistry but idk what are credits earned. is that marks or hours.
i attended community medicine classes there but did not take exam for it so should i mention it. as it is mentioned on my transcript that i attended 6 hours of community medicine classes there.
Please help me!!!