In the terrain editor you should have a button called "export terrain" (lower right). I'm not sure if that's available for Esprit, but it is for Infinite. The button is greyed out if the terrain is procedural. You have to convert it to standard, in this case.
You can export the terrain in several formats, like a heightmap (a 2D image, in several formats) or object (like OBJ format and others).