At your arrival in Fiumicino (the Airport Leonardo da Vinci) you have to reach the train line fr1 Fiumicino-Roma - starting every 15 minutes- till the station of Trastevere; the journey takes up to 20-25 min.  Every day time-table you can find here.

There stops the train to Bracciano: it is the line Roma-Cesano-Viterbo (fm3), Time-table is browseable here.

The tickets : the most easy way is to buy at the Airport only one train ticket for the whole journey till Bracciano. If you have an interail ticket , it is valid for this journey.

The camping is on the Lake, 2 km far from Bracciano ; there is a municipal bus service starting in Piazza Pasqualetti, near the Station: the line D, with this time-table.  Ask to the driver for the stop at Camping Porticciolo.