In a bowl mix the 2 flours. Whisk in the water until smooth. Cover with cling film and leave out overnight.
The next day add another 100ml of water and 100g of mixed flours. Again whisk until smooth.
Repeat this 5 more times over the following 5 days. Find a home for it - a large jar or crock or tub with a lid would be good.
After a few days you should see some action in your starter. Bubbles will appear and the smell will get stronger as it ferments. Keep up the daily pattern of feeding, but you will now need to start tipping some away each day before feeding or it will outgrow its tub! Your starter will get more frothy and vigorous. When it seems really active and 'alive' you are ready to start baking with it.
Feed your starter ideally every day. Don't worry if you miss a day or two - it will just need feeding up a bit to get its strength back.
«If your are not making bread regulary you can keep your starter in the fridge and it will keep longer between feeds. Get it out and feed it 24 hours before you are ready to use it. »