Combine now all the layers: Layer – Merge Visible (shift+ctrl+e) and continue by inverting the colors: Image – Adjustments – Invert (ctrl+i).

Smoke Effect

We have to create now a new layer, set the necessary colors in the Gradient Tool's adjustments
 
and paint the smoke with these colors.

Smoke Effect

Stretch out the gradient from the center to one of the corners and change the layer's Blending Mode on Multiply.

Smoke Effect