1 part vinegar
2 parts water
That’s all there is to it. Just mix the water and vinegar together in a spray bottle. Spray it over the stain and cover it with a damp rag. Put your iron on the steam setting and iron the rag for about 30 seconds or so, depending on how bad it is. You may have to repeat if the stain is really dark but this will work wonderfully to remove common foods and dirt from your carpet and the vinegar is a good odor eliminator as well so it works really well on pet stains.