Easiest: Assign uploaded image to a file: move between files

When uploading an new image how do I assign it to a specific folder?

Also, how to resort and move images between folders? I’ve read that it is supposed to be “drag and drop”, but cannot find any documentation explaining where and how to do this.

Did not list a page=link, because I cannot find an appropriate page.

All updates have been applied. – I’m using MacOS 10,13,3

Thank you.