Add another closing bracket } just before the line with 'class Page_Controller extends Content_Controller {'.
$has_one has also been declared twice. Remove the empty copy and rebuild the database by opening yourdomain.com/dev/build in your browser.
If you really do have no experience with PHP then I think you should consider how much time and effort you can afford to put into learning it and whether Silverstipe is the right CMS for you to be using right now.
This is because nearly all of the setup and configuration for a site is done with PHP files instead of a graphical control panel. That makes the system difficult to jump into without at least knowing the basics. The upside, though, is that once someone does know what they're doing they have more flexibility and power.