Take a photo of your current room. For best results make sure it shows the entire room in a 90° straight angle facing a wall or window horizontally (click for example). Not from a corner or angled, and not a wide angle photo as it's trained on regular photos. The AI isn't great at angled pics (yet)! Uploads + renders are shown on site but auto deleted after 15 mins. To make 100% private HQ renders without deletion and watermark upgrade to Pro and you get your own private workspace.
Mode You get widely different results with each mode. Virtual Staging mode will auto detect the construction (like walls, ceiling, beams) and tries to avoid changing it, while Interior Design mode doesn't but gives you more creative ideas. A good idea is to use Interior Design mode and then Mix w/ Original to get the original auto masked background back.