Need help with Dawn of Souls!

Hy! I am playing Dawn of Souls right now. Can somebody tell me how to upgrade my character class from warrior to knight, from r. mage to r. wizard and so on. Do I just have to reach certain level? My characters are lv 26 right now. Thanks!

u have to have an airship and fly to bahamuts island and pass his test

Stolen from GameFAQs-

To begin, you MUST have defeated the Lich in the Cavern of Earth. This will allow you to obtain the canoe (you can’t get it until you defeat Lich), and the Ship, the only two items required to start the quest.

1. To get the Canoe, go Crescent Lake (located southwest from the Cavern of Earth) and talk to the Elders on the eastern side of the town.

2. With the Canoe in hand, go to the Ice Cavern (go back to your ship, head north to the next port) and follow the river. Complete the Ice Cavern and pick up the Levistone.

3. With the Levistone in your possesion, go to the desert south of Crescent Lake (you have to jump directly from your Ship to the Canoe) and enter the middle of the desert. You’ll see a cutscene and obtain the Airship.

4. Now that you have the Airship, the world is yours for the taking! Take a look at the map and look at the middle-top of the map. To the left are the Dragon Caves, where you’ll get the actual upgrade. To the right is the "Left Wing of the Eagle". Land on the left wing and walk a long-ass way to get to the Cidatel of Trials.

5. Complete the Cidatel of Trials to obtain the Rat’s Tail.

6. Take the Rat’s Tail and go to the Dragon Caves. Land on the island with 2 holes. Inside one of them you’ll find Bahamut, the King of Dragons. With the Rat’s Tail, he’ll Class Change your characters.

Congratulations! You’re now class changed!