Tips on how to build an open campfire and on how to completely extinguish one are offered by the California Departtment of Forestry and Fire Protection.
Build an open campfire by selecting a level site away from heavy fuels such as logs (especially slow-burning woods), brush or heavy duff and needles.
Use a shovel to clear an area at least 10 feet in diameter. Scrape away all grass or needles and duff down to mineral soil. Scoop a depression in the center of the cleared area in which to build the fire and put a ring of rocks around it. Cut some wood in short lengths and light the fire. The fire must not be left unattended.
To completely put out an open campfire when leaving camp, fill a bucket with water and pour it on the fire while stirring and wetting all the ashes. Turn wood and coals over and wet all sides. Move some of the adjacent dirt into the fire and mix thoroughly. Feel with your hand all around the fire area to be sure that nothing is still smoldering.