You need to add 5 tablespoons of wholemeal rye or wheat flour and 5-6 tablespoons of water (either boiled, but cooled down, or mineral) to a 1 litre (around) jar that was washed well and scalded earlier. Mix well the ingredients to obtain really creamy texture.  Do not close the jar too tight so that the air comes in, or simply cover it with a cloth. Leave it in the warm place for 24 hours. I was keeping mine beside the heater. Now the feeding time starts!  After one day, all you do is simply bin half of it (or give it to your friend or anybody who wishes to grow his or her own sourdough following the next steps), adding the same amount of flour and water you added at first stirring well. For the next  6 days you do the exact same thing, simply feed the sourdough by taking out half of it and adding the same amount of water and flour back to the jar all over again. On the 7^th day it should have grown well with plenty of bubbles inside it. In case it has not grown by then, try to find a warmer place than the place where you kept your sourdough earlier. Some people would bake their first bread on the 3^rd day. I preferred to wait for a week before I started because at least I was sure it was full-grown.