Speak to Jocaste in the Cenarion Enclave, in Darnassus.
You now have the power to tame a pet, but you must also gain the skills to train it.
Travel to Darnassus. There you must speak to one of our most revered hunters, Jocaste. She will give you the ability to train your new pet, so make haste.
While Jocaste may seem stern, she is always pleased to see another hunter rising through the ranks. Treat her with respect and she will return in kind. Good luck, [player].