Yes make sure your file was grayscale instead of color, 513 by 513, and save it as a png file. Go into feralheart and test the height map by opening up the map maker. I suggest actually saving the height map as an actual map so you get the map folder in the terrains. Then, yes; you will make your terrain mask. Basically for this, you will need to have a 513 by 513 canvas again. Open up your height mask, copy it, and paste it on the new 513 by 513 canvas, which should be set back to color. Anchor the layer and then you will need to make three "pure" colors; blue, red, and green. They are called pure colors because they don't have any other trace of color (So they will show up as, for example, 0 blue 0 red and 255 green for green). Make a new layer over your height map, and turn the transparency down in order to trace. I normally have the transparency down to about 60% so I can see everything on my height map. Usually I fill the new layer with blue first, then use the red and the green afterwards. Once you have you terrain mask finished, delete the bottom layer and turn the transparency of your new layer back to 100%. I suggest going over with the blur tool to make sure everything is not too jagged. Now, save your file as a jpg first and then as png; this flattens out the image for you. Make sure you save both of the files in your map folder, which should be located in terrains. I hope this helped you out; it was a lot to explain xD!
