When you create a new character in Blue Saga, you get to choose between a range of different creatures from the forest family. There will be more families available in later versions.
After choosing a creature you then need to choose a base class. There are three base classes.
Multi class system
Later in the game you will be able to specialise your character by choosing a primary and a secondary class. The primary class will replace your base class. This means that your character will be able to specialise in two different classes at the same time, enabling all abilities from those two classes. To specialise in a class you need to find a trainer. There are many trainers in the world of Blue Saga, each teaching one specific class. Find them and talk to them in order to learn/buy their abilities.
Here is a chart showing which classes can be learned as primary or secondary ones and which classes can only be learned as secondary classes
Here is a list of available classes in the game, more will come.