At the ceiling box - the ungrounded fixture conductors {aka hot} for the fan and lights connect to the black wire coming from switch. The white wire from the circuit power source cable is the grounded leg conductor {aka neutral} for both the fan and light. The white wire from the switch connects to the black wire from the circuit power supply cable.
Wrap a piece of black electrical tape around both ends of the white wire going between the switch and the fixture to indicate that the wire is being used as a ungrounded conductor {aka hot}. Also do the same to the white wire going between the 2 switch boxes , as this wire is also being used as an ungrounded conductor {aka hot}.
Bare wires are together and grounded to box (if metallic) and if the fixture has a green wire or a grounding screw , it gets grounded also. Bares and green wires are equipment grounding conductors.
Be sure to read all documentation that comes with your fan / light combo fixture.
If only switched power required onward then at existing fixture
If only unswitch power required onward then at existing fixture
If switched and unswitched power required onward then at existing fixture
This is not possible with this configuration as no grounded leg {aka neutral} exists at the switch locations.
The common screw of a 3 way switch is the Odd color screw
If wiring multiple fixtures be sure to check the following guidelines concerning how to do it and what not to do: Wiring Multiple Fixtures.
If you are new at understanding the "politically correct" electrical terminology and need clarification of the terms used, we strongly urge you to read the Clarification of Definitions and Terminology guide. This will explain the terminology used in this article.