Create a Document Library in SharePoint Online
To get started navigate to the SharePoint Online site where you want to add the new Document library.
Once on the Site and logged on as an Administrator, click on the gear’s icon in the right-hand corner.
Next click on Site Contents
From the site contents page, click on + New then select Document Library.
Provide a Name for the new Document Library
Once you click on Create, you will be redirected to the newly created Document Library.
The Document Library can also be viewed and access from the Main Site on the left-hand side.