Wikipedia offers an excellent overview of The United Methodist Church and General Conference’s role and importance:
The United Methodist Church (UMC) is a Methodist Christian denomination which is both mainline Protestant and evangelical. Founded in 1968 by the union of The Methodist Church and the Evangelical United Brethren Church, the UMC traces its roots back to the revival movement of John and Charles Wesley within the Church of England. As such, the church’s theological orientation is decidedly Wesleyan. It contains both liturgical and evangelical elements.
In the United States, it ranks as the largest Mainline denomination, the second largest Protestant church after the Southern Baptist Convention, and the third largest Christian denomination. As of 2007, worldwide membership was about 12 million: 8.0 million in the United States and Canada, 3.5 million in Africa, Asia and Europe. It is a member of the World Council of Churches, the World Methodist Council, and other religious associations.
The United Methodist Church is organized into conferences. The highest level is called the General Conference and is the only organization which may speak officially for the church. The General Conference meets every four years (quadrennium). Legislative changes are recorded in The Book of Discipline which is revised after each General Conference. Non-legislative resolutions are recorded in the Book of Resolutions, which is published after each General Conference, and expire after eight years unless passed again by a subsequent session of General Conference. The last General Conference was held in Fort Worth, Texas, in 2008. The next General Conference will be April 25-May 4, 2012 in Tampa, Florida.
The event is currently rotated between the U.S. jurisdictions of the church. If the system is not changed beforehand, the 2016 General Conference would be in the West, which has not hosted since Denver, Colorado in 1996. Bishops, Councils, Committees, Boards, Elders, etc., are not permitted to speak on behalf of The United Methodist Church as this authority is reserved solely for the General Conference in accordance with the Book of Discipline.
The plenary session is presided over by an active bishop who has been selected by committee of delegates to the Conference. It is not uncommon for different bishops to preside on different days. The presiding officer usually is accompanied by parliamentarians.
Subordinate to the General Conference are Jurisdictional and Central Conferences which also meet every four years. The United States is divided into five jurisdictions: Northeastern, Southeastern, North Central, South Central and Western. Outside the United States the church is divided into seven central conferences: Africa, Congo, West Africa, Central & Southern Europe, Germany, Northern Europe and the Philippines. The main purpose of the jurisdictions and central conferences is to elect and appoint bishops, the chief administrators of the church. Bishops thus elected serve Episcopal Areas, which consist of one or more Annual Conferences.