Firstly it is necessary to make ferment. First of all it is necessary to cut bread in cubes and to make of them crackers slightly roast them on a dry frying pan or in an oven of a gas cooker. Then put crackers into a glass bank, add sugar, water and a little of yeast. Cover the bank, but not sealed. Kvass should be fermented for one day. Then you are to pour out all liquid. Keep only a part of the formed sediment. Add crackers, sugar and water again. Repeat process 3-4 times every time pouring out all liquid. First 3-4 times kvass will have bitter taste this is why it is necessary to pour out all liquid. After that you will have normal ferment which will help you to make good kvass. Do not forget every time to throw out a part of ferment, adding crackers. Kvass becomes better if after a fermentation you'll keep it for 2-3 days in densely corked bottle in a refrigerator. The quantity of sugar depends on your predilections. If you like sweet it is possible to add more sugar. But do not overlook. During a fermentation it can be formed a few alcohol. Homemade kvass can sometimes contain 1-2 % of alcohol.