You can only join the WA if your nation/s are connected to your personal e-mail address
You are allowed to have multiple nations in this game with the same email address, but you can only have one nation be in the World Assembly at any time. There are harsh punishments from NS mods if you use multiple nations in the WA, even if on different email accounts.
You can join and leave the WA at any time, and it consists of two chambers:
The General Assembly affects nations who have joined the WA, and basically passes legislation that only affects the in-game laws of your nation. This means that if the GA passes a resolution that bans the import of bananas, your nation canonically cannot import bananas, but does not affect your nation's statistics. This chamber matters to you if you prefer the roleplaying side of the game.
The Security Council affects both nations and regions and mostly impact gameplay instead of roleplay. They pass resolution that can commend notable nations or regions, condemn infamous nations or regions, or liberate regions by removing passwords imposed on their borders. This chamber matters to you if you prefer the gameplay (regions, raiding/defending, embassies) side of the game
Every nation in the WA has one vote each for every resolution that is presented to the chambers.
Every region has a World Assembly Delegate representing them, and it's always the person who has the most endorsements in that region.
Endorsements can be given and received by nations in the WA, and more endorsements increase your nation's "influence"
Influence is a statistic in your nation that basically measures what you can and can't do if you're an officer in a region. It increases gradually over time, and resets if you move to a different region.
To endorse other nations in the WA, open their profiles and scroll to the bottom of the page. There, you will see how many endorsements they currently have and who gave them those endorsements. As long as you're both in the WA and are in the same region, you can click the [ ENDORSE ] button on their profile to give them an endorsement!