Gernerally the First Appellate Authority (AA) happens to be the senior officer in administerative capactiy of the PIO. But the PIO has mandatory obligation to inform the RTI Applicant about the first AA and the limitation period i.e.30 days from the date of the reciept of the information for filing of the first appeal.
If the PIO has not informed about the same then u can approach directly to Hon'ble CIC at August Kranti Bhavan, Bhikaji Cama Place, New Delhi - 110 066 & Old JNU Campus, New Delhi - 110 067. Phone:26161137.
You can find other info on http://cic.gov.in/. You must study the CIC (Management) Regulations before filing the appeal and here the limitation period is 3 months from the date of the reciept of the information.