Below are a few training sites and videos to help you with the migration to or use of Microsoft's Office 365 applications.
Learn by particular app or service:
Interested in training on a particular application?
https://support.microsoft.com/en-us/microsoft-365/
Quick start guides:
Downloadable Quick Start Guides & Reference Cards for Office software and apps.
https://support.office.com/en-us/article/Office-Quick-Start-Guides-004185ad-d0fe-4046-85a4-5204b8b4989b