There are microfilmed records available for the town but only for the earlier years from 1809 to 1860. These must be rented through a local family history center run by the Church of the Latter Day Saints.
Registri dello stato civile di Circello (Benevento), 1809-1860
You can use this link to find the nearest location near you. The cost is about $7.50 for one roll of microfilm which is sent from the main library in Salt Lake City Utah and remains at your local center for about a month.
Below is an email address for the town's anagrafe or registry office which houses the town's vital records (birth, marriage, death, etc). You should contact this office, in Italian, to see where the more recent records are located. There is a link below with the parish info for writing letters in Italian, in case you need help with that.