i have a sourdough starter that i started 4 months ago and it is very easy. i got the starter from this website. http://www.io.com/~sjohn/sour.htm
i is the best bread i have ever had plus i made rolls and hamburger buns with it.
start with flour, water 110 degree and yeast. mix those together leave it on the counter for 2 days and than refrig. than all you have to do is take out one cup and put it aside and to the jar add one cup of flour and one cup of water 110 degrees and mix leave on counter for 2 hours and the refrig and that is called feeding your starter.
but the key to making good bread is making a sponge. to do that you take the one cup of starter and add one cup of water and one cup of flour to it and leave it on the counter overnight. i use a bread machine sometimes and sometimes i make bread by hand and either way the bread it to die for.
hope this helps