How do I protect my idea?
Copyright does not protect ideas, concepts, systems, or methods of doing something. You may express your ideas in writing or drawings and claim copyright in your description, but be aware that copyright will not protect the idea itself as revealed in your written or artistic work.
http://www.copyright.gov/help/faq/faq-protect.html
We've had long threads over the years about people stealing images off of member's websites -- there are some steps you can take to protect yourself, but nothing that will work against knowledgeable, determined thieves. (Nothing that I've heard of, yet, anyway.)
You can read about what Copyscape can do for you --
http://www.copyscape.com/campaign.php
and read about what someone thinks it doesn't do --
http://www.plagiarismtoday.com/?p=25
How to find plagiarism
http://www.plagiarismtoday.com/?page_id=19
Perhaps a member here has found a solution and will share it with you. The last advice I read was "don't put anything of yours on the internet that you are unwilling to have someone take and use for their own purposes."