Click "Customize-Interior Modeling 2.0" and select the room to enter the Interior Modeling 2.0 interface. Select the "Assembly - Light Band" list on the left, then select the modeling lines or surfaces to add the light band or light trough. You can hold the "Ctrl" key (⌘ key for Mac)) to switch between adding molding by segments or by a whole circle. After adding, select the light band and you can adjust the size and angle of the light band or light trough in the properties panel on the right.
