This is a very simple recipe, you only need water, a bar of laundry soap (like Sunlight), washing soda and borax.
Grate 1/3 to 1/2 of the bar of one bar of sunlight (the smaller 65 g bar). Put this into a large pot with 2 quart jars full of water (8 cups). Heat on medium until the soap is dissolved. I then add 1/2 cup each of washing soda and borax and still until those are dissolved. Turn off heat and add 2 more quart jars of water. Stir. (Your pot is probably getting fullish)