I have a room with a ceiling fan and light both controlled by one on/off switch. I bought a dimmer switch that has separate dimming controls one for the light and one for the fan. When I opened the wallbox, I saw three wires attached to my swicth. One was the ground, and the other two were both black. My dimmer switch came with FOUR wires - green, yellow, red, black. I know the green goes with the ground and I was able to match the red and yellow wires according to the diagram, but I do not know what to do with the black wire from the dimmer. It says to attch the black wire to the "feed wire from the circuit breaker." There are a bunch of other wires in the wallbox that are capped and connected with each other. How should I proceed?? Thanks. -Chris

it sounds like to me that you have what is called a switch loop.
the power enters at the fixture,then the hot is looped back through the switch.
that's just my guess but i am curious to hear what others have to say.

Take off the cover in the ceiling where the light/fan is, and see how many cables, and how many wires each, are in that box.

You need at least 3 wires (not counting grounds) from the switch location to the ceiling location to use your new switch. If you have only 2 (say a switch loop like LarryG mentioned), than you can't make this switch work except by running a new cable from the wall switch to the ceiling. And that's not easy to do in a finished house.

If you do not have the required number of wires at your switch box as mentioned in the previous posts and you don't want to try puling in a new cable, then you might be able to go wireless.

Check with the manufacturer of your fan for a wireless module that would be installed at the fan/light. If the module is available, installation isn't very difficult.