The place to be for this topic is here: http://www.fsdeveloper.com
That is where you find the real experts on flightsimulator and scenery creation (with Blender too).
This article also might help you
https://www.flightsim.com/vbfs/showthread.php?250762-How-to-create-photoreal-scenery-for-FSX
And on Youtube you can find some excellent tutorials, for example Austin Sass
https://www.youtube.com/watch?v=NzBrY6dzewc
