Super simple, burn wood with no airflow coming in through the bottom. You want the flames at the top, heating up underneath. Usually I’m piling wood on constantly.

When flames die down, hose it with water until no smoke.

Crush the biochar into rice size or so. I’m using a wood chipper. Then you can charge the biochar, putting in water, compost, etc. that will make it better, i spread everywhere both ways.