If you buy an ECU and Coil Pack set from ATP Electronics the fitting instruction come in the box. Also make sure you change the spark plugs and HT leads with good quality plugs, probably best from the dealer.
The full car details are always helpful especially the year as Fiat Punto's used a 1.2 8 valve model engine from 1995 but on certain models and years they had a multi-pint or single point injection system until 2000 where they then changed to a different setup but still used the basic engine type.