You need to move the character you want to fade to a lower layer than the background and the background to opacity 0.5 (or any opacity that is see through). But you can also read through this, it might help you more than my explanations:
You need to move the character you want to fade to a lower layer than the background and the background to opacity 0.5 (or any opacity that is see through). But you can also read through this, it might help you more than my explanations: