i think theres a guide on zeldadungeon ^^ id help more but i never get epona

Head to the stables called Lonlon Ranch in the middle of Hyrule field, look for someone named Malon. Hope this helps

First, you have to learn Epona's Song as Young Link, now with Adult Link you have to go to LonLon Ranch to talk with Ingo you need 10 rupees for him to let ride one of his horses, play Epona's Song so you can mount her and 50 rupees to race Ingo.

If you win twice, he'll you meet her, but he'll lock you up at the ranch, go to the yellow frence using your carrots jump over it, you obtain Epona!