This is what I know about sourdough bread.
You can buy sourdough starter, but I made mine from scratch. You mix together flour (unbleached organic, or whole wheat, or even rye) and water, cover with something breathable like cheesecloth, and let it sit till it bubbles. I added a splash of cultured buttermilk to mine as well, which gives it lactobacilus cultures for a jump-start. Whole grapes are another effective addition (that dull white coating is yeast). It’s ready when it has a layer of foamy bubbles on top.
The starter needs to be fed each time before you use it, but it can sit dormant in the fridge (or other cold place) indefinitely between feedings. If it seems a little weak after a long period of inactivity, use some to make pancakes and feed it again. But I neglected mine all summer and it was just fine when I finally reactivated it. For feeding I mix in a cup of flour, and enough water to make it pourable. If you measure, the added ingredients should be equal amounts of flour and water by weight.
My basic bread recipe is 1 cup active starter, 2 cups flour, .5 cups water, and a heaping teaspoon of salt. I mix and knead it in a kitchenaid stand mixer, but you can do it all by hand if that’s what you have. The dough is sufficiently kneaded when it’s smooth and pliable, like soft modeling clay or skin. Let rise until it doubles in size (2+ hours), form into a loaf, proof for another hour or two, and bake at 450F for approx. 25 minutes. For handformed (no pan) loaves, I usually slash the top with a knife before baking so it doesn’t explode out the side.
That’s all. After this it’s just practice, and practice, and more practice. Even the mistakes will be edible. If the dough doesn’t rise, turn it into pizza instead.
Sourdough biscuits: Cut 1/2 stick butter (4 tbsp) into 1.5 cups flour + 1tsp salt. Add 1 cup starter and a splash of cream. Mix. Bake @ 450 for 12 min.
Sesame wheat crackers: 1 cup sourdough starter, 2 cups whole wheat flour, 1 tsp salt, 1 tbsp sesame seeds, 1/4 cup oil. Split into 3rds to roll thin and cut into squares. Bake @ 300, 15 minutes on each side.
If you want a reference book, Classic Sourdoughs by Ed Wood is very thorough. The author is a pathologist who has collected sourdough cultures from around the world, and he gives detailed explanations of how and why sourdough works, including using grains other than wheat.