the above recipe is the one that I used.
sourdough takes a long time to get right.
I have been using my sour for 3 years it took about 9 months to get it to be what it is now.
If your sour is not bubbling add a lit bit of sugar to keep it alive, I make sourdough bread once a week all week the sour cures on the counter in a bowl of flour and 12 hours before I use it I soak it in water, and then make bread with it as if it is yeast I have been experimenting with bread recipes and I have found one that works really well, it rises the sourdough bread in just 6 hours!
this recipe make 6-8 loaves of bread you can cut it in half or more for less loaves
6 cups of warm water
add:
the sourdough,
1 TBS of salt
1/2 cup of sugar (don't do to much the dough rises slower with more sugar)
1/2 a cup of palm shortening (it makes the dough soft and light)
3/4 a cup of coconut oil (for some reason it rises faster with more coconut oil then shortening)
Mix until even add flour about 6 pounds (1 pound of flour for each cup of water) knead in to a dough ball leave it on the counter, it will be a bit pebbly looking clean up a bit (about 3 minutes) when the top has dried a bit you will be able to get it smooth as satin with a bit of kneading, then put it in a greased bowl and grease the top of the dough (to prevent a crust) cover it with a towel.
I suggest watching the dough until you know how long it takes for your dough to rise,
if you are late then it will collapse and taste very sour and look ugly.
good luck
ETA: and if all else fails you can buy sourdough starter:
http://www.kingarthurflour.com/shop/items/sourdough-and-crock-set