Juvenile offenses are charged differently than criminal charges against adults. They are filed as petitions and a juvenile will either admit or deny the allegations in the petition. There is no plea of guilty or not guilty.
Quite often minor offenses can be resolved by way of a deferred entry of judgment wherein the minor will complete any combination of community service, education, counseling and/or probation in order to have the petition dismissed.
Once the petition is dismissed the file is sealed and it as if the case never occurred. If your child is involved in an offense as a minor it is imperative that you consult an experienced criminal defense attorney to help them through the process.