Hello Jack M,
Thanks for your question
To do this:
Head over to the Microsoft Entra Admin Center to start the process.
Follow the steps here to register your app: https://learn.microsoft.com/en-us/entra/identity-platform/quickstart-register-app?tabs=certificate
Then proceed to complete using the steps here
You can mark it 'Accept Answer' and 'Upvote' if this helped you
Regards,
Abiola