Need info to get in Pompeii from Rome
The first leg of the train trip from Rome to Naples can be found on www.trenitalia.com. However, the second leg is on a small commuter train from Naples to Pompeii Scavi and cannot be found on Trenitalia's website.
Sorry, never been to Vesuvius so I have no information.
Try this sites
www.rometopompeii.altervista.org For to get to Pompeii and http://strictlyeurope.com/pdfs/Mount%20Vesuvius.pdf for Mt. Vesuvius
Actually, the Trenitalia site does show timetables for Rome to Pompei (with a connection in Naples), but the station in Pompei served by Trenitalia trains is not the one closest to the ruins.
As "the other Tim" said, the station you want is Pompei Scavi. When you arrive at Napoli Centrale from Rome, go to the lower level of the station and take a Circumvesuviana train to Pompei Scavi. Go here for timetables.
There are buses that run from Pompeii to Vesuvius about hourly during the day in season. Allow approximately 4 hours for the round trip. Be sure to check return schedules so you don't have a long wait for your return bus. Trip works best if there's a return bus departing Vesuvius about 3 hours after you leave Pompeii. It can be very windy and cool at the top, so take a light jacket along.
Thanks, Jhonny this site is nice