Can't Include of background image in grid-side theme

I’m super new to web development. I’ve been trying for a long time but couldn’t find a way to set a background image in hugo grid-side theme. I am not sure if there are any issues with the image path.
In my config.toml file, I have given image path as


Is there some problem with the path? Or is something else missing?

First try accessing it:

If you see the image in your browser, at least you know the path is correct.

Please give more info on the code you’re using, too.