Creating Folders
To create a new folder, click the "+" icon next to "All Folders" and then name the folder.
Unless you invite users to a folder, only you should be able to see the documents inside the new folder.
Invite users to a folder
1) Select the Folder the document resides in, and click the pencil icon next to it
2) Add the user under "invite users" and lastly click the "Update Folder" button