The darkest round cancellation, the black one, I think reads POSTA MILITARE 14. This would be like an APO number, but I do not have a list of those numbers and their locations.
The sender appears to be Dario Gioppi, as this is addressed to M. Gioppi, but he wrote his name in the wrong line on the card. The 3 fill-in-the blanks appear to be surname & name, rank, and military unit, but he wrote his name in Grado(grade) instead of Nome(name).
The censor marking would be similar to the scan below, and means something like "verified by censor."
His unit was 17th Bersaglieri Regiment, 64th Battalion. The 17th was formed in February, 1917, with the 64th, 65th, and 66th Battalions.It was disbanded in March, 1919. It fought in the Battles of: Valsugana, Castagnevizza, Tagliamento: Bridge of Madrisio, Piave: Cà Lunga, Cavazuccherina, Cortellazzo, and Vittorio Veneto.
For the later stages (Vittorio Veneto), there was a US unit - 332 Infantry Regiment - attached to the Italian 31st Division.
A perfect literary companion to your postcard: A Soldier of the Great War, by Mark Helprin. If you don’t think it’s a fabuolous historical novel with more than a touch of realistic romance, well, I’d really be surprised!