Add Files to Your Document Libraries
When you set up your personal site, SharePoint Online, which is part of the Microsoft Office 365 suite of products, automatically creates a shared document library with open permissions and a separate personal document library with no access for anyone other than yourself.
As the name implies, you put files in the shared document library that you want others to access. Conversely, the personal document library will house files you don’t want to share with others.
The traditional way of adding files to your library is to upload documents by using the Add document icon below the document library from the My Content page.
However, to add multiple documents, you can use the familiar drag-and-drop method by following these steps:
Select the document library from the left navigation of the My Content page to display the library.
On the Ribbon, click Library tools and then click Documents.
Select Upload Document and then select Upload Multiple Documents under the Name box from the window that appears.
Drag and drop files from your computer to the Upload Multiple Documents dialog box.