Download the application on any supported device (Android 4.0 and above, iOS 7 and above) and open it.
Press "See coverage" from one of the 3 main screens to check the Fon Spots coverage around you or in any city:
Press the orange search icon and then using the search box ("Search for a city").
Back to the main screens, press "Activate Now" to launch the payment platform (iTunes or Google Play):
When the payment is accepted correctly, press "Let's go!" to check the status of your connection, see the coverage, or access the menu (subscription details* and help info).
* One significant detail is the Fon WIFi app ID, which corresponds to your user account and will be needed for any related inquiry. The Fon WiFi app ID is the alphanumeric code you can find below in the "Help" section of the app > "Misc" > "What is the app ID?"