Scene > Room tab
Rooms will be predefined depending on the chosen gallery Scene but can then be modified.
Room orientation
First tumble your model to find out where the floor is.
The main issue you may encounter is the floor position relative to the model. The room may be oriented incorrectly to the model and the the base of the model may not be aligned to the floor.
A cylindrical room is generally most effective for a simple presentation of the model. Options (top right) > Room Type > Cylindrical Room
Pick the floor, wall or ceiling squares in Room Appearances to apply Colors and Appearances to the room
Check the Lock Room to Model box
Use the icon to the right of the Floor size box to align the floor to the base of the model
Use the Rotate options to rotate the room appropriately to the model
Make the floor very big so you don’t see the joint to the rear wall