If you are sure that you never had a ticket/citation and/or other arrests...no action is required from you...
If not, few resources:
your State Gov. Drive License Office (Agency)....
if you remember, the county where offence (ticket, arrest, etc) was committed, usually county/city court will have records.
Usually, it is easier to drive up there and request a copy OR court transcript in person. They usually charge a fee.
If an offence was outside of USA, then you have to contact the countries police agency or court.
However, it is important you disclose the staff you disclosed during I-485 process- if there was criminal charge....Also remember, no time time limitation for reporting these items...it says "ever"