First, I wet my face. This is recommended if you have sensitive skin because putting the baking soda on a dry face may be a bit rough for facial skin.
Next, I put a small amount of my normal cleanser in the palm of my hand and adding baking soda- maybe a teaspoon amount, though I just guessed.
Then I rubbed that all over my face.
You can leave it on for a while. Some people suggest letting the mixture almost dry and rub it around again before washing off. I did not. I rinsed it off almost immediately.
The results? Well, here's my freshly washed, no makeup face, so you can be the judge. Overall I think it left my skin much softer to the touch. Don't over do it. Use this at most, once or twice a week.