I want to add a small lake

I'm still totally confused about terrain polys and ground polys, I just can't make them work. I want to add the circled lake using the terrain polygon tool, I added the polygon around it and chose Water with Perennial Lake, then added a vector around it and chose shoreline with Lake as a tag and nothing showed up after compiling. Removed the vector and the lake showed up but looks very fake, just terrible. Tried adding the lake with polygon with other options and nothing shows up. I'm totally confused on how to use this tool properly. Is there a good tutorial just on polygons and how to use them. Not just clicking on the polygon tool and drawing the polygon that is easy the hard part is creating what you want and see it in FSX.



Resource contributor
If you did not compile the airport directly into an active scenery folder, did you copy ALL BGL files produced. The _CVX file contains the terrain polygons.
Yes, I've testing with several "Poly layers" now, a flatten poly, an Exclude General with "Airport Backgrounds" tag and then another with Landclass or Water. I'm getting some results but not exactly what I want.