A shared library is a space you and your colleagues put content into together, rather than sharing items one at a time.
How it differs from sharing an item
Shared with me is individual items other educators sent you.
Shared Libraries are shared spaces, with their own folders, that a group works in.
Finding and creating them
Click Shared Libraries in the Library section of the sidebar. Create Library makes a new one.
Your role in each library is shown beside it. See Managing who can see and edit a shared library.