Newbie with question about second classes

Forgive me for being such a goober, I tried to look up guides but I'm still not quite getting how this works.
The character I'm playing on is a level 18 Gladiator, and I believe at level 15 you're allowed to join other guilds and start leveling up a second class? I was a little late to it, but I went to the Conjurers guild and applied to be a Conjurer, and all went smoothly, but now when I try to get the first quest to level up Conjurer it tells me required class/job: CNJ.
I'm not wholly sure what this means, or what I'm supposed to do from this point, can anyone help?

Every guild wants you to equip the weapon they just gave you so that your class changes to the correct class. For the conjurer, just equip the wand provided (and maybe some clothes so you aren't naked :) ) and the quest will allow you to proceed.

Oh wow, that was easy! Thank you so much!

You should also look into making gear sets. After you create a gear set, you can put its icon on your toolbar. Then you can change from class to class just by clicking the gear set icon.