These instructions will show you how to build a basic starting point for your own Lego pony characters, in the style of My Little Pony, Friendship is Magic. You will have to figure out how to build the mane and tail yourself, as they vary significantly from pony to pony. But this should be enough to get you started :) Enjoy!
Important notes: The head requires the use of a 3x3 cross plate, which exists but isn't available in the program I used. It is represented here with a 1x3 plate and two 1x1 plates. You should also use 1x3 jumper plates in some places if you have any. They aren't necessary, but greatly increase structural integrity. You will most likely have to change the top of the head quite a bit to make certain mane styles work, so feel free to experiment with whatever looks best to you. And after you attach the nose piece, I strongly recommend booping it for good luck.