What I want is how to install, activate and update Windows

The solution depends on your current situation, is it a new PC or are you reinstalling Windows..

1

If this is a new device or if you want to clean install Windows on an existing device, you need to create a bootable Windows USB using the Media Creation Tool (second option) on this link on an empty 8GB USB flash drive, then boot your PC from that to install Windows 11.

https://www.microsoft.com/software-download/windows11

2

If you currently have Windows 10 installed and correctly activated, you can use the option to upgrade to Windows 11 using the first option on this link.

https://www.microsoft.com/software-download/windows11

3

For activation, if you have a Windows 10 or 11 licence that was pre-installed on the PC, that is an OEM licence on the motherboard and Windows 11 should activate automatically.

If you have a retail licence, then you will need to use the troubleshoot button on the activation settings window to reactivate the licence.

First, you will need to purchase the version of Windows you want to place on your computer. Then you will have to install it.

https://support.microsoft.com/en-us/windows/#WindowsVersion=Windows_11

For activation look at this link.

https://support.microsoft.com/en-US/Windows/activation/activate-windows

Once it is installed and activated you update it by going to Settings and selecting update.