How can I learn about maintaining and organizing my Mac information?

The Mac user guides are here. Search for “Ways to organise files on your Mac desktop”

macOS User Guide – Apple Support (UK)

Organize them as you would at home with hard copy: your hard drive is a file cabinet and each predetermined folder, Pictures, Music, Documents, Downloads, Movies, etc. is a drawer.

Create folders in the drawer that your document best fits, name it so you know the contents and add similar documents to it as the show up.

Normally photos and videos will go in the Photos' library and music in the Music library.

One of these might help: https://search.brave.com/search?q=how+is+mac+data+organized&source=web