is automatically protected by copyright from the moment of its creation - you don't have to register anything, or go through any formalities.
Original work can be text in the form of a letter (not may people realise that the writer of a letter owns the copyright on it, not the recipient), an article, a poem, a book, a play, a fil script, sculpture, paintings and drawings (including technical drawings and plans), lyrics, music (written and played), films, photographs, etc., etc.
It makes sense to put a copyright claim on the bottom of each page of your site - see our copyright claim at the bottom of this page - but it's not strictly necessary.
Understand that simply owning the copyright isn't going to prevent people from copying your text, the Internet's a big place, and if someone uses your work you aren't necessarily going to know about it. If you do find out that someone has taken your work without your consent, and reproduced or distributed it elsewhere you may sue for breach of copyright. In practice this is not that easy, especially if the person is living on the other side of the world.
If you really want to protect your written work then don't publish it on the internet.