Tera gold: Jousting is a fairly simple thing to do in the Coliseum of the game
The first encounter in the Trials of the Champion is against three Grand Champions of the Argent Tournament and their minions.
The exact champions you face is random each time chosen Tera gold from the opposite factions champions, meaning if you are Alliance you will fight against Horde Grand Champions and vise Versa. You can buy gold in wow prepare this combat.
The encounter is two phased. The first part involves jousting with the Champions minions and then the Champions themselves.
Jousting is a fairly simple thing to do in the Coliseum, simply grab a lance off of one of the racks around the room, equip it, and mount up on a supplied mount. From that point it functions the exact same way as it does for the Argent Tournament daily jousting quests.
For anyone that has not done these quests, you really should go and practice them a few times before trying this fight on Heroic Mode.
The instance is found in the far northern reaches of Ice-crown at the Argent Tournament grounds. The entrance is found along the northern edge of the Crusader's Coliseum and the summoning stone can be found to the east of the grand new structure.