You'll need an internet address from an already stored image.
You can get image's address by right clicking on one you'd have on facebook, on a personal blog or even one from your own posts or replies on steemit for example, and then copy pasting it in the required field.
As long as it's an image and its address begins by "https://" that should make it :)
Thank you Mr!
I’ve been absent for a few days 🙈
I will try this shortly!!!