Once you arrive at Civitavecchia train station you can take one of the CSP (Civitavecchia Public Services) or PortLink buses or walk to the port.
The CSP buses leave from the square in front of the station every 20 minutes and lead you inside the port in 15 minutes (approx). The ticket costs € 2.00 (luggage included) and can be purchased at the newsstand and the station bar.
Bear in mind: buses from the station will take you to Largo della Pace, this is the main hub of Civitavecchia port for cruises. From here you can take one of the free shuttles that depart frequently and that will take you to your terminal or to the dock of departure.
Alternatively, you can reach the port on foot from Civitavecchia Station. The entrance to Varco Fortezza is in fact about 600 meters.
Once you leave the station you have to go to Via Giuseppe Garibaldi and along the sea you will find yourself in front of the pedestrian passage.
Once you enter on the right you will find one of the bus stops. Wait at the shuttle stop, in a few minutes you will be taken to your destination for free.