How is Article 6 *The constitution, and the laws of the United States which shall be made..., under the authority of the United States, shall be the supreme law of the land; and the judges in ever state shall be bound thereby..*
and 10 *The powers not delegated to the United States by the Constitution, not prohibited by it to the states, are reserved to the states respectively, or to the people* an example of federalism in the U. S. Constitution

ok so the first one is the supremacy clause (that's not all of article 6, it says more about states rights). it means that any laws on the national level trump the ones on the state level.

the second one is the 10th amendment, which says that states can do whatever isn't prohibited by the constitution (and other amendments), not just what is specifically said they can do.

this basically shows the power balance between the national government and states government. the national government is always supreme over state governments, but state governments still do stuff. that's what federalism is.