Your Flow instance comes with a core set of useful nodes, but there are much more available from both the Tekos project as well as the wider community.
You can install nodes directly within the editor by selecting the Manage Palette option from the main menu to open the Palette Manager.
The ‘Nodes’ tab lists all of the modules you have installed. It shows which you are using and whether updates are available for any of them.
The ‘Install’ tab lets you search the catalog of available node modules and install them.