Most sites only need a single library, where all your documents live and are controlled by your global settings. That main library is published and embedded from the Publier la bibliothèque page, and the Libraries screen is empty until you create additional libraries. If you do need separate libraries with different documents or settings, you can create as many as you like here.

When to use multiple libraries
Multiple libraries are useful when you want to show different sets of documents in different places, for example a public policies library on one page and a members-only forms library on another.
Create a new library
Ouvrir le Libraries screen and click Create Library. A short wizard lets you name the library, choose which documents it contains (by category or tag), and set its columns, filters, layout, and sorting.
Embed a specific library
Each additional library you build here has its own embed code, which includes a library reference so the right one appears. Copy it from the Embed code column next to the library, then add it to your site just like any other embed. (Your main library’s embed code is on the Publish Library page, not here.)
Each library gets its own page
Every library you build also gets its own page on your library’s web address, so you can link to it directly or embed it, whichever suits.