Excel 2007 : Color coding Dates

Well I'll throw this out there like all other noobs, I haven't much experience in excel other than the usual f*rtin around with the basics. But I digress, at my job I've been put in charge of maintaining all of our fire extinguisher for several buildings and I need to keep track of the dates for when their due maintenance. What I can't figure out is how to do the formulas for the dates. I want to set it up so that 10 months out of the year the dates are in a green color, the 11th month I want it to auto turn yellow (to indicate that it's coming due for maintenance), and the 12th month turns red to indicate that it's due. Now obviously not every Fire ex. is due on the same month so it needs to be able to tell the differance throughout the year (i hope that makes since). I'm not to concerned about the coloring part of the format since I know how to do that, It's just the actual formula part I cant get. The best I can figure out is to have it change color on an exact date. Like I stated before, I need it for the WHOLE month. Any help would be greatly appreciated before I tare out what hair I have left.

CODO69