Check out Jacks page, it's a great place to start. https://www.bakewithjack.co.uk/blog-1/2018/7/5/sourdough-loaf-for-beginners

Ingredients

• 900g stong white flour
• 620g tepid water
• 16g salt
• 200g 100% hydration whole wheat starter

Method

Measure out flour and mix in salt.
Mix water and starter in a separate bowl.
Combine flour/salt mix with water/starter mix.
Mix until completely combined into a sticky dough using dough scraper or hands, whatever works for you.
Once mixed cover with a cloth and leave to autolyse for an hour or so.

I turn the sticky dough out onto a floured surface upside down with sticky side up. Stretch out gently, turn and fold into the centre a dozen or so times to start building structure. Back into the bowl, sticky side down, dryer side up. I repeat this through the day every hour or so, whenever I have time between the other things I'm doing during the day.

Early evening I start shaping into 2 500g loaves. I don't have any bannetons yet, can't get them anywhere at the moment, so I use a collander and a oblong basket lined with cotten napkin and floured to help it not stick. I shape one as a round loaf, the other onlong. Into the fridge overnight.

At around 8am the next day I heat up the oven to max, 240 degC for me, and let it soak up the heat. I take the dough out of the fridge, turn out onto baking paper and brush off as much flour as I can. A tray of boiling water goes into the botton of the oven, then I slash the dough; the round as a cross, the oblong as a straight line at around 30 degrees. Into the middle of the oven onto a large tray for 15 mins at 240. I turn the oven down to around 200 degC and bake for another 25 to 30 mins. Out of the oven onto a rack to cool ready to be enjoyed with some lovely hard cheese ro just jam for lunch, yum yum.