- buy or craft a burner (a plethora of instructions exist on the internet from all sorts of tin cans with holes punched into them, commercial models come with nice extras like lids to put out the fire, enclosures or racks to add stability and wind protection)
- find a burning liquid (ethanol grill starter most commonly called denatured alcohol in the US or Brennspiritus in my country of Germany, but even crap like gasoline, lighter fluid or alcohol based brake cleaner or antifreeze works)
- fill the liquid into the burner (about an ounce per meal), light it and wait for it to prime and the flames to penetrate all those little holes
- put your pot on top
The end. If you have a lid you can put out the fire when you're done and fill the remaining liquid back into your bottle. Can't regulate the flame, but super lightweight, plentiful fuels available wherever there's civilization, and easy to set up (unless you manage to knock it over and set everything on fire).