Petty theft under $50 can be charged as either a misdemeanor or infraction at the discretion of the prosecuting agency. It's difficult to determine whether your case was a misdemeanor or an infraction by the penalty you received. Most infractions only involve fines. The fact that you had to attend classes and do community service (assuming the community service was not a way to pay off your fines) suggests that your case may have been a misdemeanor, but you would need to check you case file to be certain. You can go to the clerk's office in the courthouse where your case was resolved and find out there. Since this case happened when you were sixteen, it is not a conviction. If this is the only criminal offense you have been involved in, you can state on an employment application that you've never been convicted of a crime. Since it is not a conviction and since juvenile records are considered confidential, it should not show up on a background check. However, to be certain that the information is never revealed, you should apply to have your juvenile record sealed.