Download the zip file to your desktop, and unzip it.

Open the directory so you see the modules and language folders.

Copy the contents of the modules directory over to the modules directory in your EE install via FTP.

Copy the contents of the language/en folder over to that directory on your EE install.

Create a folder in your images directory called “user_groups”

Make sure your config.php file is writeable (at least 666).

Go to your EE Control Panel, then navigate to the Modules tab.

Click Install next to “User Groups”.