Earthblog

Modules are the blocks of content you see off to the side of the main content area. The left and right modules are capable of being displayed in 4 styles (or colors) by assigning a module class suffix to each individual module.

You can access the Joomla Module Manager by navigating to Extensions > Module Manager. Select a position (e.g; left,right,user1,etc.) from the positions drop down menu. Select a module by clicking its title and in its parameters to the right you should see the "Joomla Module Class Suffix" field. You can leave it blank for a default look, or enter S1, S2, S3, or -none to give it a unique style.