The job of the legislative branch is to make laws. The people elect the members of Congress. Members of Congress are elected by the people of their state to serve in the Senate or the House of Representatives. A member of the Senate is called a senator, and a member of the House of Representatives is called a congresswoman or congressman. The Senate has 100 members, two from each of the 50 states.
Senators serve a six year term.
Senators must be at least 30 years old, must have been a citizen of the United States for at least nine years, and must be a resident of the state they're elected to represent. The House of Representatives has 435 members, but the number from each state varies. Each state with more than one representative is divided into congressional districts, with one representative for each district. Representatives must be at least 25 years old, must have been a citizen of the United States for at least seven years, and also must be a resident of the state and district they are elected to represent. The Democratic and Republican parties are the only major parties in the Congress.