This is the SANDBOX, a safe place to experiment with editing - just click the "golygu" tab at the top. You can do anything you want: test bold and italic, make links to a page that doesn't exist... whatever you want! You can do this without fear of damaging the many books at this site. If you would like to experiment with templates, you can try the template sandbox.
To see how to edit a page, see the Using Wikibooks guide.
The wiki automatically inserts the "Contents" box below. It is completely automatic, you only need to make sections like
== this == or
=== this ===.