Module is a container for other components. From administration panel, just drag and drop a component in a Module and validate to change a Module content. Pages from Cat model contains differents Modules with seperate configurations, to customize any page content.
Margins and orientation are customizable. A vertical Module is a customizable column, and an horizontal one is an customizable horizontal block.
Pages pane of ACS control panel show which Module is in which page : just click on the Module in the page schema to edit the right Module.