Some backgrounds in the View Editor are what is refereed to as 'skyboxes.' When you use these, your design is placed on a grassy rug surrounded by a huge box showing trees and the sky in the far distance. There are versions called Sunny Day, Cloudy Day, Sunset and Night.
In early versions of PartyCAD it was possible to construct your own skyboxes, but the process was a complicated one and seldom yielded a completely satisfactory result.
In PartyCAD 12 the same effect can be achieved by using either very large billboards or by setting up a background picture for use by the View Editor. Links to videos about these techniques are given below:
Watch the Making Billboards: People, Signs and Backdrops online video.
Watch the Rendering on a Photo online video.