This quest begins immediately after defeated the invaders of Naxos on the beach in the south west of the island. If you went on to do side quests at this point, you will find your mother still waiting on the beach. Speak with her to begin the quest. After questioning your mother, mount the nearby horse and ride with her to Naxos. Dismount when she does and speak with her again before heading to the construction of a nearby temple. After a series of cut scenes and some minor dialogue options the quest will complete.
Note: You should be around level 25 at this point. Note that you can now alter your appearance in the inventory menu without having to downgrade your armour. Any armour pieces that you have so far discovered can be chosen in the construction of your unique outfit. This also includes the visual appearance of weapons such as swords and bows.