Hello to all

Sorry in advance for my English, I go through google translation

.
I can not simulate on After effect has the depth of field

. My frame is white (. EXR).
Impossible with the exposure compensation to get a map to degrade from black to white (as in the tutorial performed by Luxion on Photoshop).
https://www.youtube.com/watch?v=B_iMUp5gVsYOr more simply, how to simulate the depth of field in After effect with the layer "Depth Pass" (.Exr)?
Someone can you help me??
Thank you
