Hi Wario,
Copyright is granted on any work you produce; it's an automatic right, and means that no-one may copy anything that you have written without your consent.
However, the value of copyright relies on you being able to actually prove that you were the original writer of a piece.
Therefore, although you have copyright as soon as you've written it, it is a good idea to get a copy of your writing indepentantly and verifiably date-stamped. If your authorship of a piece of writing is contested, this will provide proof that you wrote it before the other guy.
There are various ways of acheiving this, but the most common is to send a copy of your writing to yourself via the normal postage system, but do not open it when it arrives. The post mark on the envelope is your verifiable and independant date.
Hope that helps.
