Hi, I'm Bernard, a fellow Windows user. I'm happy to help!
You may use File History to back up your files:
Plug in your External Drive
On your PC, press the Windows key + R, then type in:
control /name Microsoft.FileHistory
Then turn on the File History.
For reference: https://pureinfotech.com/backup-windows-11-external-usb-drive/
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
Additional note: You can also manually back up the files by just copying and pasting them to the external drive.