The UN Secretariat is akin to the Executive Branch of the U.S. Government. It is headed by the Secretary General of the United Nations, Ban Ki-moon, and consists of commissions, departments, and offices with distinct responsibilities.
The main policymaking body of the United Nations, the General Assembly also serves as the main arena for debate of issues facing the member states. All 193 members of the UN are also members of the General Assembly and each country has one vote. The following links will get you started. A complete collection of UN documents from the GA is available in the Social Sciences Library, 2nd floor Paterno.
The Security Council is charged with maintaining international peace and security. It can recommend strategies for maintaining peace, impose sanctions or authorize the use of force against countries. It has five permanent members: the United States, Russian Federation, United Kingdom, France, and China who hold veto powers. In addition, there are 10 non-permanent members elected by the General Assembly for two year terms.
The Economic and Social Council (ECOSOC) is the main deliberative and policy making body that deals with economic and social issues, the environment and sustainable development. It consists of 54 members, elected to staggered 3 year terms by the General Assembly.
Established in 1945, the Trusteeship Council administered Trust agreements related to colonial territories of Australia, Belgium, France, Italy, the Netherlands, the United Kingdom, and the United States. By 1994 all territories administered under these agreement had achieved independence. In addition the TC has looked more broadly at the issue of colonialism. Since its inception 80 colonies have achieved independence. 17 non-self governing territories still exist, including the U.S. Virgin Islands and American Samoa. The TC currently only meets as required but continues to issue reports and studies related to decolonization issues..
The International Court of Justice, located in the Hague, was established under the Charter and serves as the principle judicial organization of the UN. It is charged with settling disputes between UN member states and and offering legal opinions to questions posed by UN bodies.