Anti-Federalists were completely against the Constitution and favored the Articles of Confederation (which failed). They wanted stronger state governments and a weaker federal government, which is the opposite of what the Constitution did and exactly what the Articles of Confederation did (which again failed). They also didn't want to ratify the Constitution at first because it didn't contain the Bill of Rights, so citizens would be guaranteed protection of freedom of speech and trial by jury.
Hope this helps :)