Millionaire Tips is right; intellectual property is automatically copyright as soon as it is 'fixed in tangible form'--ie., written down, recorded or otherwise taken 'into the real world.'
That means that your work is copyrighted even if it exists only as, say, a Word file--it doesn't have to published in any way, shape or form, it doesn't require that you specify the copyright, and it doesn't require that you register the copyright. You own the copyright simply because you created the work.
Of course, if it comes to a conflict, you need to be able to *prove* that you were the real creator. Registration of copyright is one way to do that; publication on Hubpages can be another; and in the old days people used to take a copy of their typescript and mail it to themselves registered mail, then leave it unopened. That way, they could show that it had been created by such and such a date.
In traditional publishing, it was usual to sell your copyright to the publisher--though sometimes it was only some specified rights--say, first magazine publication in North America, as opposed to all rights globally. I like it that HP doesn't require you to sell--but then, if they did, they'd probably need to pay. . .