tk_self uses a Django-like MTV (Model Template View) approach to implement the MVC-design pattern: the Model are the data in the (optional) database, the Template is a template-file rendered by the configured template-engine, and the View is the PHP view-function, which is responsible to handle a request and to prepare the data to publish.
To use tk_self you have to configure the tk_settings.php file in the /conf directory, write a view-function in a separate file, store that file in the /views directory and set up an URL-pattern to match to this view-function. The URL-patterns are configured in the tk_urlpatterns.php file in the /conf directory.
It's up to the view-function to return the html-code of the webpage. This can be done by returning the raw code as a string or using a template-engine. You can use any template-engine you like, but tk_self is prepared to support three template engines:
The template files are stored in subdirectories of the /tmpl directory. See the chapter about Installation for the directory-layout.