I need advice with trains

https://www.trenitalia.com/en.html

This is the official site for the Italian railway. I recommend you book all your tickets here.

Enjoy!

Just use trenitalia.com for all the train schedules. You do have to use the Italian name/spelling for the town. In general, "Centrale" is the train station in the center of town. "Tutte le Stazioni" All the stations in the city. The only reason to purchase on line ticket is that a discount might be available. Otherwise buy your tickets at the station as needed. Trains rarely sell out. And trains are frequent. All trains, except Regionale, will come with a seat reservation and you have to take that train at that time. Only Regionale trains (think bus on wheels) have open seating and you can use (with some limits) any Regionale ticket on any Regionale train headed in the correct direction.

I will get your stated. The Regionale train is 1 hr, 23 mins and 10E. The fast train is 1 hr, 3 mins for 34E. You decided if 20 mins faster is worth 20E with an assigned seat. See ----

https://www.lefrecce.it/Channels.Website.WEB/#/search-results?handoff=true&referrer=www.trenitalia.com

from Orvieto to Vietri and Vietri to Napoli....there IS a station in Vietri but when I search for it on trenitalia, it doesn't have service. I suspected as much as its a VERY slow train that doesn't accomplish much that used to go through there. You will need to take a train to Salerno and then a bus from either the station or Via Roma a block or two from the station (depending on which bus it might be, starting there or continuing through town) up the hill to Vietri. Reverse it back through Salerno to get to Naples.

But info in internet is confusing since there are so many sites that
gives you train itineraries.

Official train site- don't bother with others
https://www.trenitalia.com/content/tcom/en.html

Get the Trenitalia App so you can book easily while in Italy
A lot of your routes are regional trains so advance purchase is of no benefit- those trains can never sell out and price never changes

1) Milan to Desenzano del Garda
Milano Centrale to Desenzano del Garda
no changes
Regional Train

2) Desenzano to Verona.
Desenzano del Garda to Verona Porta Nuova
no changes
Regional Train

(from Verona I going to do a day trip to Venice ) HOW??
Simple
Verona Porta Nuova to Venezia S Lucia
There are both fast and regional trains on this route. Book a regional- time is only a bit longer than fast train

3) Verona to Modena
Verona Porta Nuova to Modena
change in Mantova
Regional Train

4) Modena to Levanto
Modena to Levanto
several options- combination of fast and regional Possibly 1 change in Milan, or 2-4 changes diff routes

5) Levanto to Florence
Levanto to Firenze SM Novella
Several combinations- best probably 1 change in Pisa
IC and regional

6) Florence to Orvieto
Firenze SM Novella to Orvieto
no changes
Regional or IC

7) Orvieto to Vietri Sul Mare
Orvieto to Vietri Sul Mare-Amalfi
Change in Roma Termini then Salerno then bus to Vietri

8) Vietri to Napoli
Vietri Sul Mare-Amalfi to Napoli Centrale
Bus to Salerno, change in Salerno- IC
regional and Fast trains available

9) Napoli to Rome
no changes
Napoli Centrale to Roma Termini
Fast Train, IC or regional

You might want to learn more about Italian trains from the Man in Seat 61. It’s an excellent site with great explanations and suggestions of train train travel in Italy and other European countries.

ChristineH !!!! OMG ! you are the best !!! Thank you so much...taking notes!!!

Philip !!! I did an I got even more confused ...is like a PHD of trains ...it is too much !!!

lol
Read this site and you too will earn your Training PhD

https://www.seat61.com/train-travel-in-italy.htm

No seriously he’s got all the info
Just ignore his advice to purchase on ItaliaRail as that is a third party reseller and won’t count towards your PhD

You just need to use the official site and know the Italian station names
Play around with it a bit

Assuming you are certain of your dates and times of travel, you should book ahead only fast Freccia trains (FrecciaRossa, FrecciaArgento, FrecciaBianca). Freccia means Arrow in Italian. Rossa=red, Argento=silver, Bianca=white. By buying ahead you can secure a discounted ticket (SuperEconomy, Economy) which may not be available as you get closer to the date of travel. The Base (full price) does not change as time passes. However discounted tickets come with strings attached. You can't change the train you booked and you can't get refunds (in some cases you might but with penalties).

No reason to purchase regional train tickets ahead of time. Regional trains are like commuter trains or subways in America. You get the ticket, validate it (date stamp before boarding, if a paper ticket), get on board. No reserved seats, seats are on a first come first served basis, if the train is full (rare but possible at commute time) you travel standing up. There are no discounted tickets on regional trains. You must pay the full base price no matter when you buy the ticket.