Once you've created & adjusted your floor plan , you can add additional items to it.
To do that simply Open the floor plan editor and click on Expand.
Then, click on the + icon from the left menu bar to open the Catalogue :
Select the item you want to add and position it on the floor plan :
You can rotate or adjust the size of the item by dragging the blue corners, as you can see in the image below :
Repeat the steps untill you have added all the items you wanted.
After that all you need to do is simply re-publish the tour in order for the changes to take effect.