OK, so you've created a library. Now let's look at managing it successfully.
Click on the library and you'll be taken to the bookshelf.
Now, to access the library settings, click on the Settings cog in the right of the toolbar (next to the New Book button).
You'll open the Settings menu, as per below:
These are your options:
Rename the library (just type over the library name)
Toggle whether or not users can access Image Search within that library
Toggle whether students can edit their own books (turn off if you want your library to be read-only)
Toggle whether or not students read each other's books
Toggle whether or not students can allow collaboration on their books
Toggle whether or not students can publish their own books online
Archive the library - you can archive the library and make it inaccessible to anyone else but you. Read more about archiving your library.
Publish the library - click this button to go through the steps to sharing the library online.
Managing users in a library
Click the Authors dropdown below the library name in the right of the toolbar. Now you can filter which books you see in a library. You can view just your books, everyone's books, or books made by a specific person.
From here, if you are the library owner, you can remove users from your library by clicking the 3 dots > Remove user.
If the user is a teacher, you'll also have the option to promote them to co-teacher.