After you file

I am confused. The information states that you "must report" the coverage from my state (Oregon) on my federal income tax return.  Like the original question, I already filed.  Form 1095-B isn't a confirmation that a private insurer or employer gave me or offered me insurance. It shows my Oregon Health Plan information, insurance that I did have.  Like I said, I am confused.  "Must" I report this as it states in the letter?  How if taxes are already filed?