You write a short story but you want to make sure your work is protected before you post it online what should you do to protect your copyright

You can add the Copyright symbol. And write a notice below your work saying that if a person has to copy or copy-and-change you work, they should contact you or something. Make sure you leave you email [If you wanna.] And if you see your work anywhere else, just report the person or talk it out with them. 

Hope that helps!! :)