Insert the copyright symbol into the front matter of your children's book. If an illustrator worked on the book as well, he can also claim copyright to the images used. The symbol should be followed by the date of completion of the work and the name of the person or organization that is asserting ownership of the work. Word-processing software allows you to insert the copyright symbol and other special characters by using a special key code; consult your Help section or written instructions.
Register your copyright with the United States Copyright Office, a division of the Library of Congress. Use Form TX, which is available online to download and print. As of the time of publication, online registration is $35.00, while a hardcopy application costs $65. You must supply information on the nature of the work, the date you created it and the publisher of the work, if you did not self-publish. Registration makes it easier for you to prove your claim of copyright if legal issues arise.
Deposit a copy of your work with the United States Copyright Office. If the work is unpublished, you will need to deposit only a single copy; you must deposit two copies of published works. You may upload an electronic copy if you register online. If you first published the book outside of the United States, then you must deposit a complete copy of the first edition. You must complete registration of the book before you can make any claims in a U.S. court.