How do I Change Background Colors?

Check this forum: lichess.org/forum/lichess-feedback/well-am-i-don-anything-wrong-thibault?page=1 how do i keep like him? Background color?

Please help me :)

EDIT: I am sorry If I posted this in the wrong forum, I don't understand where I should write this :)

You can ask @Gadhavi_Veerbhadra

Yeah, you can also upload to imgur and then paste the link on transparent option. You can insert some random images like

But, I also created a new post (in Imgur) and copied that link and when I paste it here (in transparent) it does not come? What's the problem?

@Qwertise, do mention the "https://" before the link

Tema xorocha

Not working :( imgur.com/gallery/S0GLq5g