You can use these files to inject/add any code you want in this theme.

By default this file includes examples like "footer.sample.php" which must be renamed to "footer.php" to work properly.
The same goes for "header.sample.php" -> "header.php", "style.sample.css" -> "style.css", etc.
Basically, the structure is file.sample.ext so you must remove ".sample" from the filename

footer.sample.php	-> Bundled example
footer.php		-> Real file to be included