Speak with Colosos at the Argent Tournament Grounds to become a valiant of the Exodar.
You've proven yourself worthy of competing under the banner of the Exodar, <name>. Now, you should introduce yourself to Colosos, who leads the Exodar delegation. As the draenei grand champion, he will enter you into the tournament on behalf of the city and oversee your training and testing as valiant.
It has been an honor working with you, <name>, and I wish you luck in the competition ahead.