Apple has created an online iPad User Guide for everything you need to know about iPad:
https://support.apple.com/guide/ipad/welcome/ipados
There is a specific section on how to view files and folders using the Files app:
https://support.apple.com/guide/ipad/view-files-and-folders-ipad49b77901/ipados
There is a specific section on how to organize files and folders using the Files app:
https://support.apple.com/guide/ipad/organize-files-and-folders-ipadeb120505/ipados