Well I tried to keep a sourdough starter but gave up on it, getting some from somebody else would be so much easier. Here is a basic recipe for bread.
4 cups wholemeal flour. (1/2 + 1/2 + 1/2 + 2 1/2 cups.)
1/2 cup of sourdough starter.
1/4 teaspoon of sea salt.
1/4 cup lard, beef fat or butter.
2 cups water.
You mix the starter with flour and water a little added at a time in 3-5 hour intervals then add the rest of the flour and ingredients after 3 feedings and risings. Refrigerate until ready to use, let it warm up and rise before baking, 325F for 45min.