Jan 24, 2014 - 09:49 AM
You will have to take the Circumvesuviana from Sorrento to Naples, which is a private train line and tickets are bought at the station, from Naples to Rome you may take a high speed train that can be booked on Italiarail.com as well as the tickets to Florence and Venice. These tickets will not be available to book until 90-120 days prior to departure.
From Venice to Lake Maggiore it depends what town you are going to . you will end up taking a ferry as the train only goes so far.
The railway line goes only partly around the lake. You will therefore need to use other means to get to the main tourist destinations.