TYPO3 v8 has reached its end-of-life March 31st, 2020 and is not maintained by the community anymore.
You can order Extended Long Term Support (ELTS) here: TYPO3 ELTS.
How to create plugins with the Extbase framework and Fluid templating engine is handled in depth in the chapter Configuring the Plugin in the "Extbase / Fluid book".
There are basically two ways to create plugins in TYPO3:
With the Extbase framework using
configurePlugin()in the file
registerPlugin()in the file
Create a plugin using
Generally speaking, if you already use Extbase, it is good practice to create your plugins using the Extbase framework. This also involves:
creating controller actions
create a domain model and repository (if your plugin requires records that are persisted in the database)
create a view using Fluid templates