[andrewas]

OK, there are spoilers ahead. You have been warned.

To become a mage you need to get a mage to train your. I used sebastion in Lower Clarks Ward, but apparently the woman in the hut in Ragpickers Square can train you earlier. Ratbone (possibly), also in Ragpickers, can trian you as a thief. Several fighters throughout the game can train you as a fighter. To change to a class you talk to one of the trainers. The fighter trainers can also give you weapon proficienies depending on your level.

Once youve been trained in a class you can switch back to it by talking to an appropriate NPC. For a theif, Annah, and for a mage dakkon. For a fighter, dakkon or vhailor. You cannot be a priest, but the one you get is good enough anyway.

You only gain in one class at a time (no dual or multi classing for you) and your other classes have no effect at all. So a level 20 fighter/level 5 mage does not gain *any* advantage from his fighter levels, apart from HP.