On day 1 you will mix 1 cup of flour and 3/4 cup of water together in a glass bowl. Cover with a towel and let sit on the counter for 24 hours.

On day 2 through day 5 discard half of the starter and add 1 cup of flour and 3/4 cup of water. Mix into the starter, cover with a towel and let sit on the counter for 24 hours.

On day 6 and day 7 discard half of the starter and add 1 cup of flour and 3/4 cup of water. Mix into the starter, cover with a towel and let sit on the counter and repeat every 12 hours instead of 24.

Now on to the maintenance... You will need to feed your starter and the amounts all depend on how often you use it and where you will be storing it. I like to store mine in a 1/2 gallon mason jar in the fridge because I don't use it every single day. I will typically get it out on Saturday morning and use it during the day/evening and then leave it out until Sunday and make any other baked goods. Then I feed it and put it back in fridge. If it's stored in the fridge you'll need to feed it once a week. If you store it on the counter you'll feed it daily. The amount you feed it will depend on how much starter you keep on hand. So if you have 2 cups of starter you will need to feed it 2 cups of flour and 1 1/2 cups of water to keep it well fed. If you want to build your supply up you can also feed it more than equal parts. Say you have 1/2 cup of starter and you want 3 cups for a big baking day you can add 1 1/2 cups of flour and about 1 cup of water to build up your supply.