In this section, we'll be placing actors, so we'll be mostly working in the 3D view. Close the Geometry tools window, click on the Camera Mode button, and save your work. First we'll place a light. It is easy—right-click on the ground, then click on Add Actor | Add Light (Point).
The light should appear where you clicked. Go to Lit mode, and you'll see your room appear with lighting now, though it looks a little strange, since the light is right on the floor.
Move the light up from the floor so it's in the middle of the room. You can also increase or decrease the light's radius using the Scale tool. Give it a try.
The last thing we need to do before we run is to Bake Lighting . Right now the light is calculated dynamically, which is expensive and unnecessary. If we bake it, it calculates texture maps for any light and shadows in the scene, which is much cheaper. Click on the Build Lighting tool that is right next to Build Geometry. The default...