I invite you to watch video on You tube about baking a sourdough bread at home.
This movie may help to get better breads.

Use this link http://youtu.be/oq1GJad-bFI

Starter

To make a good bread it is good to have a good, old culture starter. To get it, you may use the eBay. There is a fantastic starter from San Francisco, for only 2.50 BP. Please try this link:
 http://www.ebay.co.uk/itm/181171389282?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

The starter is a living thing,  you may grow it and keep it for ever. You may keep it in fridge and feed once a week or just in the kitchen and feed it every day. For baking a sourdough bread is enough to have about 100 - 125 ml of it.

Sourdough bread

Ingridients :
Stage 1
- starter - 100 - 125 ml
- wheat flour - 150 g.
- rye flour - 100 g
- water (clear, not chlorine) - 250 ml
Mix everything, live for grow under covering for few hours

After 5 - 10 hours .....

Add :
- 250 g wheat strong flour
- 50 g. very  strong wholemeal bread flour
- 50 g rye bread flour
- teaspoon of oil
- salt - 2 tsp
- few drops balsamic vinegar
- water - 250 ml. or more
- nuts ( sun flower, sesame,...)
- mix everything 

Live under covering for 3 - 4 hours

Put the dough to pan loaves...

 Leave for grow 5 - 10 hours

Bake 60 min at temp 200 C ( top and bottom )

Cut when cold.