You speak to Team Leader Muha @ coordinates:(x: 307, y: 427) , and he will have four quests;
They will be called:
- Path of the Fighter
- Path of the Hunter
- Path of the Spellcaster
- Path of the Acolyte
You may choose of the quests and once you complete it, you will become that class. Once you change classes, you gotta stick with it.. so choose wisely.
For more information see:
You can see your coordinates under your mini-map to your top right.