CISCO Networking Academy: NDG Linux Essentials (free, 70 hours, level beginner, online self-paced, language: English) https://www.netacad.com/virtual/wr/linux-essentials

GCFGlobal Windows 10: (free, introduction to using Windows 10): https://edu.gcfglobal.org/en/windows10/

Skill Share: Windows 10 for Beginners: https://www.skillshare.com/classes/Windows-10-For-Beginners/135214918?via=browse-rating-windows-10-layout-grid

GCFGlobal: What is an operating System?: https://edu.gcfglobal.org/en/computerbasics/understanding-operating-systems/1/

GeeksforGeeks: Intro of Operating System: https://www.geeksforgeeks.org/introduction-of-operating-system-set-1/

CISCO Networking Academy: An Intro to Cybersecurity (free, 15 hours, level: beginner, online self-paced, language: English) https://www.netacad.com/virtual/wr/intro-to-cybersecurity