Hello @nicholaspanetta,
To add the background image of the page you need to go to the Page—>Select the Page and click on the EDIT button.—>Scroll down you can add an image here. Please have a look at the given screenshot below.
There is the option of body class you can add a custom class and then you can add this custom CSS code to add the background color of the page background.
body.custom-class {
background: #295eaf;
}
Please feel free to change the background color code as per your design. Please note you can change the CSS custom class name, if you change the CSS class name you need to change the CSS code as well.
The purpose of providing custom CSS is to show you how to add CSS code to your site. Writing custom CSS is outside the scope of our theme support. If you need more customization, you need to learn CSS and learn how to use the browser’s element inspector.In case if you have no idea about coding you can subscribe to One where customization questions are answered.
Hope it helps.
Thanks