open wv3viewer (dl on this site in tools section) and find a terrain tile, then extract it and open the extracted file with some art program. edit it and save, import it in ur map and set path to: TerrainArt\*the tileset that uses that terrain*\*file name*.blp
well u did the wrong path, look, u got to fill in this: TerrainArt\Cityscape\*ur file* and yes it must be blp, so just find the convert function on wc3viewer, its soe asy to use
well it should be there, where before filling in the right path, the white marble was. so try making terrain with the white marble and c if its the imported terrain
yes it should work automaticaly, and if the editor detects it, then the path isnt wrong, but maybe another tile uses the path. u should try using all terrains of cityskape and maybe even others, like dalaran, maybe its somehow on one of those