Reading the FAQ (http://www.nationstates.net/page=faq) answers your question...
Second, you can endorse other UN members, which is a way to signal that you like their policies, or their leader, or their cool flag, or whatever. The nation with the most endorsements in each region is appointed Regional Delegate, and gets to wield additional influence.
Finally, you can propose your own resolutions. If approved, these go in the queue to be voted on by the entire UN. You may, however, be required to possess a minimum number of endorsements first.