Here’s a good reference for you to get a simplistic overview of the parts of the U.S. federal government and what they do. This source also provides some basic agency contact information. To get a real notion about the U.S federal government check out this web site. It will get you started. We all need to know the truth about our nation. Not what others want us to think of as the truth. Know for yourself.
USA.gov Government Made Easy
Remember that regular people work in these agencies and work hard every day for this country as directed by their leadership.