To connect to the Wi-Fi, you need to be near a NEMO hotspot.

See the map of hotspots

Open the Wi-Fi connection setting on your device (PC or mobile) and select the network named NEMO
Enter your access code

The first time you connect, click on Register to obtain an access code by SMS. This code can be used at all NEMO hotspots. From time to time you may be asked for a new code

Make sure you read the sections on "Rules for use" and in particular the general conditions of use