How to apply decals in nXt 5.5?

The help on this topic seems woefully out of date, thus my reason for posting here.

I modeled a bridge in Rhino 6.0. Now I want to place it over a rectangle with a decal. The decal is an aerial photo of the bridge site.

How is that aerial image applied to the rectangle? Seems to me this should be a simple thing to do. But the Help docs on this issue are terrible. There is no Properties List, and there are no “Flamingo nXt Decals.” Clicking the “Texture Mapping” icon shows icons for a variety of texture mapping types, but no decals or “Flamingo nXt Decals.”

Please update the Help for this very basic texture mapping feature for use in Rhino 6 with Flamingo nXt 5.5. (Or tell me how it’s done!)