• A theme has a template and styles.
• A theme is a set of Views. In this way, you can develop any themes you want but not affected the main process.
• A style is a set of images and css.

Now lets go to Admin→Home > Site Manager > Themes Manager > Create a New Theme (See image) and fill the fields there shown. The only really important fields are the name and the based on, but it doesnt hurt to fill in the others too.

• Name: the name will be displayed in Theme Manager
• Key: it is to think about what the plugin will do, and make a unique key for your plugin. Key only contains letters, numbers and the underscore '_' with no space. Ex: redtheme
• Based on : it is the theme that the created theme is inherited all layouts and styles.
• Others field are optional

After that, the theme is created and all theme's files will be auto generated.

Example: Lets fill the fields like this:

At this point we have a theme and source files for template. Now lets go to the source file and check at root/app/View/Themed/Mytheme and root/app/webroot/theme/mytheme