Under United States copyright law, as the creator of your original thesis or dissertation, you own the copyright to your work as soon as it's in a "fixed and tangible medium," such as saving your work to your computer.

Kent State University Policy 5 - 10. 1 also specifies that students own the copyright to their coursework, including theses and dissertations (see Kent State University Administrative Policy Regarding Copyrights). 

Registering your copyright is not necessary; however, there are certain circumstances in which it can be advantageous. If you wish to do so, see detailed Copyright Registration instructions.

If you have any questions about this, please feel free to contact Cindy Kristof at ckristof [at] kent.edu.