Hello,
Sorry but the trial license doesn't include support for custom scripts. We recommend you to check the available examples and the documentation available on http://www.phpdocx.com/documentation/introduction/html-to-word-PHP
About single background you need to add it as a watermark using this method available in Corporate and Enterprise licenses: http://www.phpdocx.com/api-documentation/docxutilities/insert-watermark-Word-document-with-PHP
Regards.