The primary early game magic vendor is located above on the map.
There are ruins here with a large flower and a mini boss inside. You have to defeat the Pumpkin head enemy in order to open the door behind it. Inside of the door behind the boss you will find a woman with a mask. Talk to her and she will teach you some magics if you want.
You can have her learn new spells by finding arcane scrolls throughout the game.
To learn new Faith Incantations you will have to wait until about 4-5 hours into the game. Eventually when you return to a Site of Grace the maiden will pop up and invite you to the Round Table Hold. When you go there you will find a man in monk robes who will sell your Faith spells for a price. Similar to the magic user you can bring him books to get more spells.