Train from Rome to Naples

Trenitalia and Italotreno are the actual train companies
Purchase from those sites

https://www.trenitalia.com/content/tcom/en.html
https://www.italotreno.it/en

Both also have easy to use apps
Purchasing in advance will save you some money

Italiarail is a reseller

Your post is a tad confusing
Are you taking train next am or on arrival to Rome?
If you plan to go straight to Naples I would purchase tix on the app once you land
Pre purchase will save money but not if your plane is delayed an you miss your train

Leonardo Express info
No need to pre purchase
https://leonardo-express.com/en/en-leonardo-express-tickets/

There are no flights from Rome to Naples; the distance is too short.
Depending on when you land, there is really no need to stay in Rome; the trip from the airport to Naples takes about 3 hours: Leonardo Express from the airport to Roma Termini, then high speed train from Roma Termini to Napoli Centrale.

As for where to take the train: once in Roma Termini you will see huge departure boards. Look for the train number of the train for which you bought your ticket: it will show the track #. Destination should be Napoli Centrale or Salerno but there might be some exceptions.

There is free wifi at Fiumicino Airport, so you could buy all the train tickets via app after collecting your luggage.

Otherwise, At Fiumicino Aeroporto station ask for a through ticket to Napoli Centrale.

All trains have a number (something like AV XYZW) just like flights. If you can't find it on the ticket, ask at the counter to point it out for you.

Once in Roma Termini station, look for that number on the "Partenze - Departures" board.. Your train will depart from the platform listed in the right column, headed "Binario Platform".

You could take the airport train run from Trenitalia and an Italotreno train from Rome to Naples. Nothing wrong with it, just be aware that Italotreno has no counters at the airport: You should make 2 separate purchases, either online or at the counters.

We get into Rome about 10:30 pm, so we just wanted to stay the night, and we will take the train the next morning. We used to fly Alitalia into Naples, but they are no more, and as of right now Delta is telling me there are no flights. Its really no problem to take the train, just wanted some tips on that since I haven't done that in a long time.

Thanks so much for your replies and advice!

we will take the train the next morning

If this is the case you won't run the risk of missing the train and you can buy the Rome-Naples ticket online, to enjoy the discounts for early birds. Print it out and look for these train numbers: https://images.app.goo.gl/7kt1ood6vtSYJdAn7 https://images.app.goo.gl/jCFv14ApxrGtHiXU6

I have already deleted This week's email from Italotreno, but I think that the discount code is LANA. You must use it before January 31st and travel before May 3. Subscribe Italo's newsletter to receive more codes.

Thanks so much for all of the info!

Keep an eye out for ticket sales...I got two-for one tickets Rome-Naples on Trenitalia a couple of years ago, for a total of E19.

We took Italo from Rome to Naples and it was great.

I always use trainline.com…great app. Will show all options…trnitalia, italo, etc. tickets right on phone. Good throughout Europe and UK.