Sparkling theme fullscreen

I’m working for the first time with Wordpress and am creating a website with sparkling. When I write the text for my landing page and add the cover picture that goes on the top(right under the header), both isn’t full screen. It appears in a white box. I am trying to make white background box disappear so that the picture is full screen and the text has only the background color that I chose in the background. Now I can see the color I chose in the background, but everything I write in the Gutenberg editor appear as if it’s on a white paper (re white box) on top of the background I chose.
I can’t find a solution anywhere.

Also, I can’t add the copyright notice. I added it in the menu in the footer, however it simply doesn’t appear.
I’ve searched anywhere, even for codes for both problems, even though I’m a complete newbie with Wordpress and coding.
Could you please help?
Thank you!

Hey there

Please provide direct link to the page with background image, I will check it