In short,
every 4 years, all citizens over 18 years select the deputies as lawmakers for the general assembly.
the general assembly selects the state president for the term of 4 years.
the state president proposes a best man for the post of prime minister.
if the general assembly agrees, the prime minister forms the government for the term of 4 years.
the rank of power in the country is as follows:
the chief of the communist party
the state president
the prime minister
despite the chief of the communist party is the rank highest, but he has no executive power. his role is to define the rules of action. the state president has more or less the function of ceremonial head of state. the prime minister is the man who holds the excecutive power.
the general assembly controls the government. it has the right to hold vote of confidence for all major top leaders, including state president and prime minister. the assembly has the supervision over the state budget. it can veto any major investment decisions of the government. For example, the general assembly refused the proposal of Japan highspeed train Shinkansen, because it is too costly ($60b).