In the game called Maple Story how do you get animals and then how do you ride them

Well, You gotta be a certain level first.
If your a ordinary Mapler, Such as, Theif, Bowman, Magician, Pirate, or Warrior, You can get the Hog at level 70. Sadly, You will have to pay a price of 20 million mesos.

Once you reach Level 120, You can trade the Hog for a Wild Boar. you don't need to pay anything Luckily. But I do remember that you have to get 400 of something o.o"

Then once you reach level 200, DANGGGGG You can trade the Wild Boar for a Dragon. It gives like 190% Speed :D Maybe 200% I forgot ]:<

If you are a Cygnus, You can get the Bird (Don't know the name o.o") at level 50. It costs 10 million mesos.
Cygnus' have the same thing for 70 and 120. I forgot the name because I don't play Cygnus'...