Copyright is an incidence of creation, so "Once you create an original work and fix it, like taking a photograph, writing a poem or blog, or recording a new song, you are the author and the owner." However, federally registering your copyright gives you additional intellectual property protections, so it is worth considering, especially for valuable IP. This page from the U.S. Copyright Office discusses what rights registration provides you and this page provides you with video tutorials for registering your copyright.
Copyright is beyond the scope of our work in the Patent and Trademark Resource Center, but if you reach out to the PTRC Representatives we'd be happy to point you to additional resources. We can be contacted by email at lib-ptrc@osu.edu.