DNS Spoof on a Wifi Access Point

Hello my fellow hackers,

My school has a WiFi Access Point without any password and the students always use it (I'm a student too). They use it on their phone, computers, etc... I am not trying to get their facebook password nor their mail password, only their Pronote credentials (it's a french service used to look your grades up on a special website, HTTP only, no HTTPS). Everything is ready for the "acquiering of logins", the website, the fake dns server, etc...

But the only thing that is not ready is the "DNS Spoof" on the WiFi Access Point. How do I spoof the Wifi's DNS settings on all the devices?

I hope you'll be able to help me,

thank you ;)