Speak with Zul'tore at the Argent Tournament Grounds to become a valiant of Sen'jin.
You've proven yourself worthy of competing under the banner of Sen'jin, <name>. Now, you should speak with Zul'tore who leads Sen'jin's warriors. As the troll 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.