The Three Branches of the U.S. Government

In order to understand how a bill becomes law, you must first understand how the U.S. government works. There are three branches of the government. The Legislative branch, the Executive branch, and the Judicial branch.
1. The Legislative Branch is described in Article I of the Constitution; it is comprised of the Senate and the House of Representatives; it makes and passes laws and the national budget; it votes on bills; approves the appointed federal judges and can declare war. Congress is the legislative branch of the federal government. It is bicameral, comprising the House of Representatives and the Senate.
The House of Representatives consists of 435 voting members, each of whom represents a congressional district and serves for a two-year term. In addition to the 435 voting members, there are five non-voting members, consisting of four delegates and one resident commissioner. There is one delegate each from the District of Columbia, Guam, Virgin Islands, and American Samoa, and the resident commissioner is from Puerto Rico. House seats are apportioned among the states by population; in contrast, each state has two senators, regardless of population.
There are a total of 100 senators (as there are currently 50 states), who serve six-year terms (one third of the Senate stands for election every two years).
2. The Executive Branch is described in Article II of the Constitution; it is comprised of the President of the United States and his Cabinet; it enforces laws; makes treaties; and the President signs or vetoes bills. The executive power in the federal government is vested in the President of the United States, although power is often delegated to the Cabinet members and other officials. The President and Vice President are elected as running mates for a maximum of two four-year terms by the Electoral College, for which each state, as well as the District of Columbia, is allocated a number of seats based on its representation (or ostensible representation, in the case of D.C.) in both houses of Congress. The executive branch consists of the President and delegates. The President is both the head of state and government, as well as the military commander-in-chief and chief diplomat.
3. The Judicial Branch is described in Article III of the Constitution; it is comprised of all the courts in the land; it interprets laws and punishes lawbreakers; it decides whether laws are constitutional or not. The Supreme Court is the highest court in the federal court system. The court deals with matters pertaining to the federal government, disputes between states, and interpretation of the United States Constitution, and can declare legislation or executive action made at any level of the government as unconstitutional, nullifying the law and creating precedent for future law and decisions. Below the Supreme Court are the courts of appeals, and below them in turn are the district courts, which are the general trial courts for federal law. Separate from, but not entirely independent of, this federal court system are the individual court systems of each state, each dealing with its own laws and having its own court rules and procedures.
Read more about the United States Congress on Wikipedia.org