Is the Trenitalia the proper site to find times and purchase tickets for train from Zurich, Switzerland to Naples, Italy?
When I plugged in the cities it told me I had "invalid departure station" and "invalid arrival stations" Thanks!
The Trenitalia journey planner needs you to enter the Italian names or spellings, so try Zurigo and Napoli (Tutte le Stazioni). When I do that I get a number of trains listed, mostly with a change in Milan. You can also buy tickets on the Swiss railways site www.sbb.ch - with prices in Swiss Francs. The journey planner there seems to list much the same trains.
Kim, I'd suggest trying the sbb.ch website, as you should be able to buy tickets online there. That trip appears to be about 8H:45M, with one change at Milano Centrale. The time will vary slightly if you're departing from Zürich Airport rather than Zürich Hbf. I briefly checked the fare for a date next week, and it was listed at CHF 201 PP. Happy travels!