@pusangligaw : here's the answer for your question JC guide - ElWiki
-it's very detailed so you will be able to finish the quest without any problem (aside from the drop rate)
-you can visit elswordhq.com because you will see most of the answers there.
-if you're goin to do a job change, you need to finish first the chain quest before you'll have an option to choose one of the two jobs that is available for the character
-if you're doin a job change quest, it's always indicated by a BLUE tag in your quest list