Copyright ensures that you have the sole right to publish and reproduce your works in any form, with the exception of the user rights granted by the Copyright Act (e.g. fair dealing, educational exemption).
You do not need to apply for copyright for the works you create. Whenever you create an original literary, dramatic, musical or artistic work, copyright automatically applies. While it is common practice as part of the publishing process to sign over your copyright to the publisher, creators are starting to ask for the option to retain some or all of their copyrights.
Here are some resources to get you thinking about copyright and your rights as an author.