It would be best first that you understand the parts of our theme for you to be able to easily change the stuff that you need.
Though the interface screenshots in the documentation I'm about to show you was taken from the Customizer, don't worry. They have just been moved to WP Admin > X or Pro > Theme Options.
Let's first tackle the header part.
Here are the related documentations to customize the header area of your particular setup.
If you wish to design the Header and Footer separately, you'll need to use the Pro Header and Footer builders. You can learn about the Pro Header and Footer Builders in this video tutorial: https://theme.co/apex/forum/t/pro-header-and-footer-builder-introduction/103
For the content part, you need to know about the page templates available in X/Pro. You can learn about page templates in our Page Meta documentation: https://theme.co/apex/forum/t/meta-options-pages/144. Once your familiar, select the Blank - No Container | Header Footer page template for your page which should make your content span fullwidth of the screen instead of fullwidth of the container.
The last part you need to learn about is the Footer. Here's our documentation about Footer Options: https://theme.co/apex/forum/t/customizer-footer-options/136