How to add the screenshot of the theme showed in the market and in the Firefox theme page?

Hi to all,
I created a new custom theme.

Saved, exported and added to the browser and also added as private project in the marketplace but… when I open them active theme page my theme is listed without any screenshots. How can I add a screenshot to show the theme aspect as other theme have?

Thank you!

The screen is added only if the theme will be listed to the public on the marketplace.

All fixed…Thanks…