This tutorial will explain how to apply a module class suffix in Joomla!. This tutorial depends on the available styles for individual templates. Some settings may be different. See the templates corresponding docmentation for more information.
Go to your Joomla! administration console

Go the administration of your website at ww.yourjoomlasite.com/administrator/
Login to your Joomla! administration

Enter the username and password you created when installing Joomla!
Go to the Module Manager

Navigate to Extensions > Module Manager
Go to the module you want to edit

Select the module you want to apply the Module style..
Apply the Module Class Suffix into the parameters to the right

Apply the Module Class Suffix. (S1 example shown)
Save the Module Setting

Click Save