How do you Copyright one of your stories on here?

I'm in the process of righting a story and it is my pride and joy and I really don't want to risk getting it stolen. Thanks if you know!

Also, since I have to fill up space: You should check out my story because it would make me super happy. You should also comment and tell me if there is anything you think I should change. Please be specific though! Here it is: The Chase Of Our Lives

Please help me get my story copyrighted! Please be specific in giving the details of this process, I can be slow sometimes when it comes to directions.