Hope my tutorial helps anyone. I know its hard at first!
Ive seen people asking how to level up your horse:
TO LEVEL UP A Horse what i do is ill go and fight thats the EASIEST FREE WAY to level up your horse. Horses go up to lvl 10 in a single tier. Breeding them can make the tiers go up.

thanks for this awesome vid! quick question: where are tame-able horses located? ie which areas/zones?

Go to the map then tap a area that says wild horses and just go to a spot on the map that shows a horse :)