Expanding Folders in File Explorer

There are several areas to the File Explorer window, including the folder navigation area. Here you will find the hierarchical layout of the folders on the PC. But it is usually just showing the top level of the folders.
Use Up and Down Arrow keys to move through them.
To expand folders to look at the sub folders inside, position on a folder and press the Right Arrow key. To collapse the folder, press the Left Arrow key.
To expand all the sub folders in a particular folder, press Control + Shift + E.
To view the files in a particular folder, move to it in the folder navigation area, press Enter to open it and then press F6 to move to the list of files.