This must be done in either your CAD program before rendering and uploading to Yulio, or in Photoshop before uploading to Yulio.
This process can vary depending on the type of image and software you're using.
For a panoramic image, you can create a plane with the same aspect ratio as the image and add the image as a material.
For a hemispheric or sphere image, you can use the same technique, but with a sphere.
Here's a post on backgrounds and landscape views.
Check out our YouTube channel for more info & tutorials: https://www.youtube.com/channel/UCsZs0SQp_fiQEe2pfvfJkBg/featured