If you're reading this you've either written a book or about to finish writing one. You may want to self publish or you may be seeking the more traditional path of trying to submit your book to a writing agent or publisher.
But the bottom line:
What do you you do now?
1. Protect yourself and your work.
In the US, any work you create is technically yours under copyright law, however, if someone decided to steal your work, the burden of proof would be on you. Your best bet (and your safest bet) is to invest the $35 and get an official Library of Congress Copyright registration You can do this part all on-line. The piece of mind is worth it!
Once you have protected yourself with copyrights for your country (or countries where you will be submitting your work) you are safe to proceed with steps two and three.