Exhaust fan hook up. I only have black and white from source. Please help
You're going to need to run new wire, which can be tricky. 

ASSUMPTION - There is a wire from the panel to the switchbox.  If the supply goes directly to the fixture first, then this does not apply!!!


Turn off power to the circuit.
Remove the existing fixture.  See if you can get the mounting box out.  
Feel along the wire and remove the staple attaching the wire to the structure.
Do the same at the switch box.
Hopefully, your wire will move now if you pull it gently at one end.
Take some 14-3 wire and strip a few inches of the outer insulation off. (A dull carpet knife works great!)
Tie one of the strands of the new wire to one of the old.  Wrap the entire connection in electrical tape.
Pull the old wire out, and the new wire will follow it in.
Replace staples to the best of your ability.


If you can't get the wire to move, you're going to have to break and patch the drywall, which can be a pain.

Wiring
 - The other wire in your switchbox should be the supply from the panel.
 - Cut two pieces of black wire, and pigtail them to the supply black with an appropriate sized wire nut. (You are splitting the wire into two).
 - Wire each end of this pigtail to a separate switch.
 - Wire the 14-3 black to one switch, the red to the other.
 - Wire the whites together with a nut.
 - Connect the ground to the box and the supply ground.
 - Connect the fixture at the other end according to manufacturers instructions.


Put the switches back in the box with one screw each.  Make sure the connections don't touch.  
Test.
Reinstall the other screws, faceplates etc.

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