Hey Laurent,

There are two ways to configure the wi-fi.  The first is as you said, through a monitor.  This does take a significant amount of extra electrical power, so make sure you've connected the Pi to a power source that delivers at least 1 amp worth of current.

The other way is to access via SSH and follow this document:

https://www.raspberrypi.org/documentation/configuration/wireless/wireless-cli.md

Let me know if you have any more questions,

Milan