Maria, buenos dias!
A few suggestions that might help with the "confusion".
First, be sure to check the documents that were provided with your Rail Pass for the details on the "7 PM rule". I believe that if you start your journey after 19:00 (7 PM), then you only use one day on your rail pass.
Regarding your rail journeys, I checked the bahn.de website briefly. There's a direct train departing Paris Austerlitz at 19:45, arriving Madrid Puerta de Atocha at 09:58 (Time 14H 13M, no changes). Reservations are compulsory, and these are NOT included in your rail pass - you'll have to pay the reservation fees separately.
For the trip from Barcelona to Rome, you might consider a budget airline rather than train, as that's a LONG trip! The travel times on that route are about 23-29 HOURS, with between 3 and 6 changes! Vueling and ClickAir both fly that route and the lowest fare I found was about Eu$50 (the fare will depend on which date you choose).
As this is your first trip to Europe, I'd highly recommend reading Rick's Europe Through The Back Door, especially the "Rail Skills" chapter. Also, be sure to wear your Money Belt and be alert for petty criminals (Barcelona seems to have a bad reputation for that).
Good luck and happy travels!