How do you hook up two ways switch to three ways?

Your 2 switches will have 3 terminals each. One will be copper colored and two black.

You will require a 12-3 WG wire between the switches.

The Travelers: The black terminals will be connected together one from switch a to switch b and the other from switch a to switch b, it does not matter which black terms you choose to go from switch a to b

The brass terminals one will go to the light switch a and the other to a power source switch b.