As a follow on to my reply above.
It is very hard to explain "file management" in a text reply.
Here is a simple video explaining a bit about Windows file management (only a small part).
The video shows only ONE window open but to use external hard drives you can have TWO Windows open (one for the main drive, the other for your external hard drive).
Then you can "drag" files or folders from one window to the other to move or copy them (or select copy in one windows and paste i nthe other).
The only way to "learn" is to practice. Practice creating and deleting folders, practice moving files between folders, practice copying files between folders and so on.
Do this with NON important files in case you make a mistake and delete them.
DONT move or copy important Windows files or program files, only move or copy your personal files.