People write the constitution. There is no established rule or limit dictating how many people are required to write the constitution.
By the authority of the people, governments are formed, according to the rules that have been laid out and agreed upon in the constitution.
The constitution establishes the country that the people now belong to and the rules that determine how it will be run.
People are the government.
Do not be afraid to create your government. You have that right and you are not doing anything wrong if you choose to exercise it.