Press final to view the physically accurate ray-traced version of the scene. Wait a few minuets for full quality to accumulate. Press preview to open the real-time view, where you can select the lights and move them.
This is a port of my C++ project: Photon Engine. Everything is 100% made by me. The C++ version is a lot better as it has a quadtree based preview system, and the final mode is also real-time. (It also has a blender-like customizable GUI, and light settings). This project has the basic engine, but without some of the optimizations that are not possible in scratch. I possibly could have added GUI for light size, etc - but I wanted to finish this in a morning for scratch week!