How do you add a picture to your story?

You know when you see the stories and there's photos on the left next to the title? I'm at my fourth chapter in my story and I still have not been able to find how to put a picture in that small box...If you could help me much would be appreciated :)

And while you're at it...If you're interested, would you like to read my story? Called "Stay Forever."
I love reviews, and I'll review a piece of work in return ;)

Since I have to have 100 characters..I love making new friends so feel free to stop by and chat anytime on my profile or wherever :)