Thanks for reaching out.
To have full width parallax, please walkthrough following steps:
- Click on the settings cog icon on left hand panel.
- Under Page Settings > General > Page template select Blank - No Container | Header, Footer.
- After that Add Section in the page and inspect the section.
- Under Setup > Background click Advanced.
- Add background image in Background Lower Layer or Background Upper Layer.
- To enable Parallax, you can do so under Background Parallax > Lower Layer.
To learn more about the options mentioned on above steps, please take a look at following resource.