dotCMS folders and file assets are managed from the Site Browser. The dotCMS Site Browser is broken up into two main sections - the Site Browser directory hierarchy and the Browser detail section. Clicking on a folder in the Browser directory tree reveals the contents of that directory in the detail section. For more information, please see the Site Browser documentation.
All Files Assets and Pages can be created from the Site Browser. For information on Adding File Assets from the Site Browser tab, please see the Adding Files and Adding a Page documentation respectively.
For a fast and convenient method of uploading multiple files, please see the Upload and Edit via Webdav documentation.