I've been using this for over a month now (straight baking soda, no detergent added) and it's working great and I'm saving money!
1) Just add baking soda to your washing machine in place of laundry detergent. About 1/2 cup to 1 cup per load gets the job done for me. Adjust tomeet your own needs.
2) If you don't think that alone will get the smell/dirt out, you can add a tablespoon of regular detergent. Very simple!