If you're planning a trip to Portofino, you won't have a direct train to the town. In order to reach Portofino, you'll have to take the train to the nearby Santa Margherita Ligure.
This is the train station which also serves Portofino.
To reach Portofino then you have 3 options:
The ferry: is the fastest way to reach Portofino. The ferry port is very close to the station, but I'll pin all the details for the ferry in the dedicated pin.
Walking: going to Portofino walking is certainly an option, my personal favourite if you have no rush and want to see more of the coast. It's a 5 km walk (about 3 miles).
The bus: located just outside the station, take the bus 782. It has a standard ticket of €5.