How do I make back not black?

Hi I have simple question how make black background of game use some kind of picture if it's possible.

left is what it looks, right is what I want.

Add an image (or 2 images) under everything.

Check it in "z order bar" (activate it in "view")

Suggestion 1: add an image in the game background, I do not recommend using flat color.

Suggestion 2: use "layers" Background / game / hud layer

Edit index.html under body tag:

w3schools.com/cssref/pr_background-image.asp

Is is possible to make it in engine so when I export in nwjs it will work in exe file?

I would think you would need to edit the nwjs template found under:

Construct 2\exporters\html5\templates

I would think you would need to edit the nwjs template found under:

Construct 2\exporters\html5\templates

So this will customize background if scaled on any aspect ratio because game render in 1:1 aspect.

That depends on what css you use, repeat, cover, etc.