The installation of the standard MediaWiki extensions is quite simple. What you will need to do is download the extension archive and extract its content in the “extensions” folder of your MediaWiki installation. Once you have done this, open your LocalSettings.php file with a text editor like notepad and add the following line:
You should substitute NewExtensionName.php with the exact name of the extension you have installed.
It is recommended to check the ReadMe file provided with the extension in case there are additional steps to install the specific module.