I hope you will not mind a response in English. Feel free to use an Italian translator as necessary.
You don't need to worry about assigning IP addresses to those NICs. ESXi handles the IP addresses, and what you're showing probably indicates either a cable pull on the down NIC or an up-stream problem with the port (assuming it's plugged in). Before deciding that you need another physical NIC, perform the obvious and basic troubleshooting steps first.