1. Add an item with a light source to your room. IE *CEILINGCENTRELIGHT1 from Universal Lighting or *Aquarium 3 from 2020 Cloud
2. Select the item and go to Items Lights
Here you will be able to alter the light colour and intensity. You can also select a custom colour by clicking More Colours in the colour drop down.
If you have a manufacturer's light colour you are trying to replicate, you can either add the RGB or HSL in Items Lights Colours MoreColours Custom. Alternatively, if you have an image, you can use the Colour Picker tool and 2020 Fusion will replicate the colour.
*The aquarium below has had the light colour changed to 2020 Fusion Orange
In addition, if you do not want the item to appear as a light source, you can turn off the illumination by navigating to Items Lights and selecting or deselecting as shown below.