How to wash laundry with Zote?

Currently, I don’t have access to a washing machine. I bought a bar of Zote (blanco). What is the proper, traditional way to wash clothing with it? Do I grate it and soak the clothes? Do I scrub it on a washboard? Or, do I just rub the soap directly on each item, then rub the fabric together? Sorry if I’m over complicating this, I just want to know the traditional method that gives the best results. Thank you.