Welcome to editing terrains. You are correct that the editor doesn't have much info on it. It is kind of trial and error and mucking around.
The terrain files are generally in the graphics directory. Default and each mod will be in a separate directory, and some are better organized than others. For ANewDawn, the directory is graphics/at2 where you will see directories like fredfield, fredjungle, fredmud, etc. In the directory, the main graphics that goes in the main input (with the blue arrow and is visible under all tabs) is Field.png. This will have multiple images that will be used an provide some randomness in what is put on the map.
Then, there are the edges, which are under the "64 Special Sprites". These are used to provide a transition between different terrains so that they don't have sharp, hexagon edges. There are two ways to use these, the easy way and the hard way. And there are times when the hard way is exactly how you want to do it. The easy way is the Fred Sprite sheet, which is a single image with all 64 sprites in the same image. The hard way has 64 different images, with a letter and number. The letter denotes how many edges are in the image, and the number is basically an index for the images needed for this type of edge. So, b is for one edge, c two, etc. The default in the editor is the hard way. The way to change the special sprites is to click the button next to "x64" right under the name. (I am not sure but if there no sprites, there might be an arrow). Anyway, clicking this will remove the sprites. If you choose the Fred sheet, then you navigate to the directory and select the image. For the hard way, you give the name of the directory where the 64 images are, and they will be loaded.
To figure out which terrains cover which other terrains, look at the "Graphics Overrides" tab. This will bring up a "Graphic Overrides" menu showing which terrains these edges should cover. These have to be loaded manually, which can be MIND NUMBINGLY BORING. The priority is determined by the z=VALUE. The terrain with the highest z-VALUE wins. The other window is for terrains that will be treated the same when ExtraExteriorSame=True. This is a bit more advanced, but a key example is "sea" and "stormy sea". The edges will be drawn so that they are treated the same. So, the coast will be smooth if a sea and stormy sea are adjacent.
There a couple other things you want to know eventually. One is a border. Off to the right is the button "PerHexBorder". This will select a terrain graphic as a border to be drawn. It will generally overlay others and can be useful. For example, I use this to smooth the interface between mountain terrains of a different type, and between wooded forest and pine forests. That way there isn't a sharp interface in the images between regular and mud mountains.
Even more advanced is the interior graphics, with "InteriorDrawingStyle=True". Instead filling the hex with edges that overlap other images, these are interior and they flow into other hexes. This is DCC1 style, and is how terrain in graphics/alt should be used, which you can easily see in say alt/Field/d14.png the terrain connects interior hex edges. This is a bit tricky to get used to.
The graphics/at2 file has the graphics for the medium size. You will also see graphics/at2SMALL and graphics/at2BIG. These have the small and medium hexes.
BTW, if you select the "No Climate" option to create a random game, there should be no climate in Four Seasons.
If you want to make terrains, and have them be seamless I can give pointers on that too.
< Message edited by Ormand -- 1/13/2021 9:39:30 PM >