Using a glass container of some sort (I like these), weigh out both flours and water, then stir together.

Cover loosely with a lid or plate.

After 4-6 hours dump out half of the starter in the garbage, feed to the chickens, compost it or make pancakes with it. And repeat steps 1 & 2.

Continue repeating these steps until the starter is doubling itself in height (this is why I like tall cylindrical containers, it's easier to see when it doubles), has air bubbles and smells slightly sour.

After it is doubling you can feed it and store it in the fridge so you don't have to feed it as often (the fermentation slows down) and take it out when you are ready to bake.

Before you bake you will want to refresh it again using the same steps above!