Roles

[Enkidoh]

Once you've unlocked the Armoury System you can join up with as many or as few class Guilds as you wish - once you've joined up to switch to that class you just equip it's weapon or tool into your weapon slot. If you want to switch back to your original class you do it in the same way. It's better to join ALL Guilds though, as it's all easy experience and that way you can try every class and get a feel for them whether you want to actually take up that path or not.

[Naberrie]

Not to derail the thread but I am also new and have a similar question. I just finished the level 10 gladiator class quest and am curious about joining other guilds. Can I choose to go down a armourer/paladin path or am I limited to one only? A nice detailed explanation would help quite a bit as I am finding info on such matters scarce.
Thanks!

You can level every class or job on one character. Paladin is the job form of Gladiator. It requires a level 30 Gladiator (with the level 30 Gladiator class quest completed) and level 15 Conjurer to unlock. You then do a quest and your Gladiator becomes a Paladin.

Armorer is a crafting class that makes gear. You can unlock it in Limsa once you finish your level 10 class quest on whatever your starting class is.