Every city will have its own government. There will be responsible for drafting a charter for the city, and then abiding by it. The charter will dictate when elections are held, who can run for office, who can vote, how long will officials remain in their positions, etc. Each neighborhood within the city will have one or several city councillor and the city will have a mayor. The by-laws as well as the charter will be voted on by both the councillors as well as the mayor. Each city will have it's own laws that include such thing as tax rates, who can become a citizen of the city, etc.
Each country will have a national government. This will be made up of a Head of Government, and government officials. There will be a constitution that will dictate how the country is run, that is similar to the city constitution. So, it will detemine things like when elections are held, who can run for office, who can vote, how long will officials remain in their positions, etc. Each city will have one or several officials represented, along with the Head of Government, and will vote on laws. Each country will have it's own laws that include such thing as tax rates, who can become a citizen of the country, etc.
Every country will send representatives to Alpha Nations. This international body will be responsible for keeping international peace and security among the countries. It will promote international dialogue, and will attempt to keep rogue nations in check. There will be an elected Secretary-General, and then ambassadors from each nation which will vote on non-binding resolutions that are meant to encourage nations to keep the peace.