The videos you can find here all show specific parts of the Administration and how to perform tasks there.
Administration
This video will guide you through most of the administration, and show you how to manage users, create teams, where to find your subscription details, and how to look into audit logs.
SMTP Configuration
This is a guide fro configuring your own SMTP servers. It shows both the Plain SMTP set up as well as Microsoft Graph API.
The use of custom SMTP is a paid add-on.