WiFi hotspot are not common in Italy.
You need some luck to be close to one.
If you've got an unlocked phone with bluetooth and GPRS/EDGE,UMTS(WCDMA) support, I would suggest you to go buy a TIM prepaid SIM card (you get it in minutes and it'll be activated in a few minutes too) and pay around 20-25€ to get Internet.
TIM provides Internet over GSM, GPRS, EDGE, UMTS, HSDPA, TIM WiFi Hotspots included in the option (you can get up to 9Gb of data for 20 or 25 euros!).