Extensions
You can install node libraries to your project.

Use the searchbar to search for available libraries. Click on Install button to add the library to your project.
This page also displays the list of Installed libraries. To remove a library from your project, click the Uninstall button.
Removing a library will remove all nodes that are provided by this library from your Data Flow. Before removing a library make sure that it's not used in your Data Flow
Usage
The newly installed library will be available in nodes menu Installed libraries.
Use it like any other nodes.

See library documentation to create a new library.