Model and background won't show up in render

Dear community

First of all, I want to say I’m new here with the program :stuck_out_tongue:
I was doing a model with lines and I added a background. You can see a model in a background. Here is the picture:

And then after I have entered ‘render’, I go a view without model nor background. I checked ‘show’ below the wallpaper properties and on viewports properties. Here is the picture of render without background nor model:

What should I do?

Okay, it kinda solved it but there is still a problem about the wrong colors, but when I turn on ‘gray’, then the background dissapeared after render :p: