To add backlight, follow these steps:
Select the Wall: First, choose the wall where you want to add the backlight.
Access the Tiling and Cutting Tool: Navigate to the tiling and cutting tool within your design panel on the left side.
Add the Shape: Within the tiling and cutting tool, locate the "Add Shape" option. Use the line tool to draw the outline of the area you wish to tile.
Apply the Outline: Once you've accurately drawn the outline, click the "Apply" button to confirm your selection.
Give It a Extrude Property: Select the newly created tiling outline and assign it the "Extrude" property in the design panel option.
Assign it a Thickness: Under Depth field, type in the desired panel thickness.
Front Shift: Under Front Shift, specify 0.
Material Selection: Clone the material applied on the shape and in the Material Editor, assign it an Emissivity ranging from 10-30. Select Clone and Apply.
Finalize and Apply: Select the Back to Designing arrow at the top right. You will return to your design with the backlight added.