The Files app on iOS 11 would let you save and access the files containing in the onboard storage of an iPad tablet as well as that on iCloud, Google Drive, Dropbox, or other compatible cloud based storage services. In fact, the files you store in iCloud would pop up automatically in the Files app, but you should configure other cloud storage services in order to access them in the app.
For that, first download the compatible cloud based application onto the device and launch the Files app from the home screen on your iPad. Then, navigate to Locations > Edit and tap on the respective toggle to enable the app that you want to use via the Files app. Tap on Done once you are done with the integration.
The cloud service app would let you find and organize the files stored on iCloud including pages, keynote docs, and even numbers. When making the changes to them on an iPad tablet, the edits get updated on all the other iOS devices linked to iCloud as well.
You can also move the files from iCloud to different locations in the Files app. For that, go to Locations > iCloud Drive icon and tap on the On My iPad folder. Moreover, you can also create a new folder in the internal storage of the iOS device or the iCloud Drive or the third party cloud based service you linked with the Files app. For that, navigate to Locations and tap on either iCloud Drive or on Dropbox, and then select On My iPad. Then, slide down on the screen and tap on the New Folder icon, key in the name you want for the new folder, and tap on Done.
It shall be noted if you cannot see the icon denoted by an empty folder with a ‘+’ sign or if the new folder is grayed out on your iPad tablet, then the third party cloud based service does not support new folders. You can also send a link to any of the file on iCloud from the Files app if you want to share the file with a friend. For that, select the file, tap on the Share icon denoted by an arrow on an empty box, and then choose from AirDrop, Mail, or any other preferred option to share the file.