The Views/template directory contains a header.phtl and a footer.phtml which should be included on every new page generated. To add additional pages just edit the file header.phtml to add the extra link and then add a new Controller (pageN.php) and a new View (pageN.phtml), for each page required.
The Model code files are placed in the Models directory.
Do not change any of the css files in the css directory!