You will start with equal amounts of water and flour, feeding the starter daily. You will need a kitchen scale and a glass jar with a loose lid. Alternatively, use a glass jar and cover it loosely with a kitchen towel. I have included a 6-day schedule which is the time it took me. But a colder environment can take longer. So, don't worry if your progress is a little slower than mine.
Day 1: Mix the flour and the water in a glass jar. Stir vigorously with a spoon to ensure that all the flour is incorporated. Cover it loosely with the lid. It will look and feel thick and sticky. Keep the jar in a warm, dry place.
Day2: Now you start feeding the sourdough starter. You should be able to see one or two bubbles. If you cannot see any, don't worry. Depending on the conditions of your kitchen, it may take a bit more time.
Weigh the jar and discard half the batter. Now add in the equal amounts of flour and water (4 ounces each) for today and give it a thorough mix. It should be thick and sticky. Cover it and keep it aside.
Day 3: Your starter should start showing signs of life with bubbles. It should also be visibly larger in volume with a slightly sour and musty smell. Now it's all about the same story. Weigh your jar, discard half the starter and feed it flour and water for today (4 ounces each). Again, make sure all the flour and water is mixed thoroughly. You may hear the bubbles popping.
Day 4: Your starter will start to expand more and more as you get ready to feed it. By now you've got the drift. Weigh the jar, discard half the starter, feed it the assigned flour and water for today and leave it.
Day 5: Need we say it? Weigh and repeat.
Day 6: By now your starter must have doubled in size since yesterday. It should look bubbly, frothy with that trademark sour aroma. When you move your spoon through the batter, it will feel less gloopy. Your starter is ready to use!