Production and distribution are state controlled and the state owns the machines, factories and stores. A central government body comes up with a plan of what to produce, how to produce it, when to produce it and for what purpose.
Tasks are than distributed to factory managers and production targets are set.
In practice the central body met, in the USSR for example, every 5 years or so.
Market forces have no place here. Regardless of demand, production goals must be met.
Command economies were regarded as a more efficient way of catching up to the west for the eastern bloc countries.
“We are fifty or a hundred years behind the advanced countries. We must make good this distance in ten years. Either we do it, or they will crush us.