To make a good sourdough bread you will need some sourdough starter.
1 c four
3/4 c water
stir and let sit for a few days. after 3 days add another cup flour and more water and stir. The next day remove half and add fresh flour and water stir well. It may separate and that is fine. as it is colder it may take a few more days to achieve that "smell" that is so distinctive.It took me a full 2 weeks for it to ferment. Every few days stir and remove one cup - throw it away and add 1 c flour and 3/4 c water for great help on starters you can go to http://blog.kingarthurflour.com/ and they have great pictures too.
Come back tomorrow and I will have sourdough for your bread machine. I know a lot of people are interested in bread machine bread especially around this time of year as the weather cools.