I have got to the part where you have to choose between the mages and a..

Check the handy walkthrough. If you can pick between the 7 jobs,
after you go to the healing place, where you meet a gnome. He will give you the spell(s) mini(to get multiple, learn, then talk again) then turn mini, and go to the southern forest part. After doing your thing there, go to a cave, where the vikings are, talk to the boss viking(no, you do NOT have to kill him) and he tells you theres a draon ravaging the seas, ships broken etc. If you stop it, you get the last ship left. After speaking to him, leave at the north exit. Do NOT go on sea, you WILL get killed by the dragon(2 people 1500 hp each turn). Instead go around the top of the ocean/sea/whatever till you reach a temple. You find a dragon with a missing eye(stone don't worry) and go through dungeon, defeat giant rat, obtain second eye, place in dragon. After that the dragon will become peaceful and you will get the ship after speaking to the viking boss again. The rest I leave for the walkthrough because this is getting too long.

You said you don't know what to do after smashing that big rock with the airship right? So that means you have cid in your party. Go through where the rock you smashed was and go into the city if you want to catch up with cid after he ditchs you go to the op left of the town to go to his house.he will tell you that his wife needs an elixer (whitch can be found in the city) give his wife the elixer and there will be a sort cutsence where he opens a path to a place for you to get items afterwards go to to every1 in town in every house (thats the best thing to do anywere in this game itll keep you on track with what you have to do)