read the FAQ and did a quick search but couldnt find answer.

I just bought the game last night , just doing the first few missions with isabel . Picked light magic as one of my abilities/skills , i'm lvl 12 now yet i dont seem to have any light magic spells.

how do you get light magic spells?

You have to build mage guilds in your towns, then have heroes with light magic visit them to learn the spells. Every new level mage guild nets you more powerful spells, but you have to have the right skill level to learn it.