The Complexity of Congress
The official government website for Congress. Includes all the information you need about Congress, it's members, current legislative activity, and more.
No textbook can substitute for the live coverage of the House and Senate provided for free to the public by C-SPAN.
Major news outlets all have reporters covering Congress, but they only report on the flashiest stories. Roll Call reports directly from Washington, D.C. and has a cadre of reporters who are specially trained in all things Congress.
https://www.archives.gov/founding-docs
Read and learn more about the Founding Documents of the U.S.