...
With your themes, you can assign blocks to specific routes and even overwrite active blocks/controllers with your own HTML.
Modifying an HTML Block/Controller
In order to modify an existing HTML block or controller, you need to create these files within your html/ folder in your theme. For this example we are going to modify the "Friends Online" block that shows up in a user's dashboard when they are logged in. This means, we try to overwrite the HTML block file PF.Base/module/friend/template/default/block/mini.html.php. There are two ways for you to do this:
...
To make sure the changes take place, clear your site's cache from the AdminCP.
Creating a New Block
In addition to modifying blocks, you can also create a new block. Similar to apps, themes can bootstrap a PHP file called start.php. From this file you can add blocks and use any of the API Functions provided to apps.
...