"The judicial Power of the United States, shall be vested in one Supreme Court, and in
such inferior Courts as the Congress may from time to time ordain and establish."
Article III, Section 1, U.S. Constitution
The MAIN task for Congress from the quote above was to -
F appoint members to federal courts
G
consolidate state and federal courts
H determine how to set up the lower courts
J establish qualifications for federal judges