There are two types of directory areas for Storage:
With your TidyHQ account, you get 25Gb of Storage space free.
If you have the Storage App installed in the Files area, you are able to upload your files (documents, images etc) and create your own directories.
Alternatively Communicate, Events, Finances, Meetings, Pages, Shop, Tasks and Sessions are Smart Folders - that is, when you include an image or document (or any other file) as an attachment, those files are automatically stored for you (to re-use or for record keeping). These files can be found in the Archive section.