What does the tenth amendment have to do with american federalism

The Tenth Amendment says "The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the People.". Federalism is the relationship between US State Governments to the Federal Government. 

Any good federalist governments share government power between the central government and the state/local governments, which are outlined in the Tenth Amendment.