Mike is right that what he wrote is copyrighted - not only his creative lines from, what I certainly hope is, his forthcoming novel (the beginning intrigues me!
), but also his entire post. As soon as any work is in tangible form, it is automatically copyrighted.
Registering your copyright gives you added protection, and it can be wise to register your book when you are shopping your book around to publishers. It is not, as Mike said, necessary, but it can be prudent.
For information on how to register your work, you can go to the U.S. Copyright Office's official website -
www.copyright.gov - and you will find your questions answered there.