Trying to get background image to display, followed instructions, didnt work

I am trying to add a background image. I created a directory in the config folder called www, and called the picture day.
In the raw lovelace editor I added this line:

background: var(--background-image)

In the template the code says:

  background-image: 'center / cover no-repeat url("/local/day.jpg") fixed'

But the background does not display. Any suggestions?

You need to restart after creating the www folder.