Use the opening screen to work with template libraries. The whole screen is dedicated to the job and you get access to the Info Data panel which allows you to review the data for the currently selected template (screen shot below).
You can add, clone (copy), delete, view, edit, import, export, backup, restore library templates as shown below. You can also save the libraries by clicking on the Save toolbar icon (libraries are also saved when the program exits)
See also the Data templates tutorial
To add a template:
Cloning a template creates an exact copy of the selected template gives the copy name 'Copy of ...' followed by the name of the original template.
You can view the details of a template in the Info | Data panel on the right of the screen as shown in the diagram above. Note that icons in the View panel indicate that you can click on the template to see its' details. You can also use the Previous and Next Navigation buttons above the Info panel to navigate through previously viewed components and templates.
Note: You can work with templates with a file open from the Templates tab on the Navigator panel but in this case you're working with Model Templates, i.e. templates specifically associated with a particular model not the library.