You can create as many folders and sub-folders needed.
From the home page of your project :
- Select the section < Documents > in your project.
- Click on < Add the documents>.
- In the new window, choose < Add folder>.
- Type a name for the folder. Select < Create >. A new empty folder appear in your screen.
- Select the newly created folder and add some documents.
- Click on <Add documents>.
- Drop your documents directly from your computer. Click on < Create > to validate.
To go back to the basics on the documents page go here.