For the mane, look into your FeralHeart > media > textures > masks
There should be a file called "fmaneMask.png"; it should be black with little spike things on the bottom. Open this file
Now, color the mane directly over that. Make sure to lock the layer (to not accidentally color in areas you don't want to) and that alpha channel is on ^^ (Basically, you want to see the little spike cut-out things, which mean it's transparent, which shows as a grey checkerboard thing. I'll send a picture if this is confusing lol). Once done, just send it to whatever preset folder you're using (make sure the name of the file matches up and that it's a .png) and you should be good to go c: