08. To create the windows of the lefthand side building, use the Pen tool to create Shape Layers in white. Next, select all the windows layers and merge them (Layer > Merge Layers), rename the layer ‘Windows’ and set an eight-pixel Gaussian Blur.
09. Duplicate the ‘Windows’ layer and give it a Gaussian Blur with a radius of 25 pixels. Illuminate any other windows using the same technique. Remember to duplicate the layers and add more blur on the duplicated layer, as this will make the lights brighter.
10. Move the windows layers to the Lights folder to give them the same Color Dodge blend mode – this will make them behave like real light.