Pause Menu dim the background how-to

Basic Pause Menu for what I’m working on it already functional, how can I do some effect to dim the backgound in the pause menu, and undim it when the game resumes?

How about just adding some black background with the opacity of like 0.3? Maybe on construct gradually increasing from 0 to 0.3 and the other way around when you want to close it.

Try to use UMG