Here are some furniture samples you can use for learning how to upload furniture, or you can use them to make variations of colors and styles!
These samples are collected as a Unity Package. To add them to your Project after downloading, open the Unity Project you have the Sinespace pack on. Right click in your Project Window, and choose 'Import Package>Custom Package'.
Choose the downloaded Furniture Samples package, and it will add it to your Project window. You should see this: