For a new federal law to be enacted, it must start as a bill and be approved by both the House of Representatives and the Senate. Congress passes the bill on to the president to sign it into law or veto for revisions.
First, a representative presents a bill as an idea. A committee then evaluates and develops the idea. After the idea makes it through the committee stage, the committee passes the bill on to the rest of the House for debate and voting. If the House of Representatives votes the bill through, it moves on to the committee stage in the Senate and follows the same process. After passing the vote in the Senate, the bill moves on to a joint committee of both House and Senate members to work out any differing details in the versions of the bill approved by each branch. Then the bill goes back to the House and Senate for a final approval vote.
Once the bill receives approval in the exact same format by a majority vote in both the House and the Senate, it finally moves on to the president. The president can then sign the bill into law or veto the bill and pass it back to Congress for revision.