Hi Robert...I can't imagine that I can help you, but here goes and you may already know this part!
Choose color in tool box (foreground) that you want the smaoke to be.
Select the area of the image you want the smoke to appear in...(lasso), and set feather amount...have to experiment for each type ofapplication of course.
Go to Filters>Render>Clouds. I hope this helps. Dorothy