The Gladiator is the default tanking job in Final Fantasy XIV: A Realm Reborn. With a sword and shield, the Gladiator's main purpose is to generate as much enmity as possible, holding the hate of the enemy (mob) in question. While the Gladiator inflicts a decent amount of damage, it is not a damage-dealing class. Leave that to the Archers, Lancers and Pugilists.
If you start your game as a Gladiator, you'll end up in Ul'Dah. Follow the main storyline quests and you'll end up at the Gladiator's guild before long. Start your Gladiator class quests and try to complete the level 10 quest before you head off to other cities in the airship (via the storyline quests). When you get to Gridania, speak with the receptionist at the Conjurer's guild. If you've completed the level 10 class quest, you'll be able to unlock the Conjurer class. You'll need to get this class to level 15 if you want unlock Paladin when your Gladiator reaches level 30.
As you level up, you'll learn new sword skills, but the higher you level the more skills you'll learn that increase enmity. These are the skills you'll want to use during party play and dungeon runs. The Gladiator specializes in tanking single mobs, but he can handle a group during the early levels of dungeon runs. Skills such as Flash work against all nearby enemies, so make sure to have it readily available when tanking dungeon runs. Flash uses MP, which makes it great in combination with Riot Blade, which restores MP.
When you reach level 18, you'll learn the Shield Bash ability. This stuns most enemies and works very well when they're attempting an area attack. Always have this action ready to use. It has a 2.5 second recast timer, so it won't be down very often. However, don't spam the action unless you see the mob attempting to perform an attack that you'd like to stop. It won't stop every attack, especially during boss battles, but it does well to stun most enemies you'll encounter during dungeon runs.
It's important to alternate between the Gladiator's various skills to ensure that you're maintaining hate, while keeping the important skills readily available. You'll also need to keep an eye on TP usage. Some of the Gladiator's actions such as Shield Bash and Riot Blade use TP. If your TP is too low you won't be able to use these actions. Focus on actions that don't use as much TP, such as Fast Blade or Savage Blade, and save the strong, more TP-heavy techniques for when you really need to get a mob's attention.
In terms of gear and stats, vitality (VIT) is an important stat for Gladiators. It increases their health and defensive abilities. Strength (STR) is also important for holding hate and dishing out damage. A Gladiator isn't about damage dealing, but every bit of damage helps to hold hate, especially when the real damage dealers will be dishing it out in much higher levels than you will.
We'll have more advanced Gladiator tips coming your way in the very near future. Stay tuned to Prima Games for more Final Fantasy XIV: A Realm Reborn beginner's guides, as well as some video content coming shortly after PAX Prime!