Excel 2007 : How to highlight a cell in Col. A, if the date in Col. B is greater than date in Col. C

I've got a Procurement spreadsheet that I'm using to update my PMs on their various hardware orders. I need to highlight a blank cell (in Col. A) with a specific color (e.g. green/yellow/red). But that color depends upon if the Ship Date (Col. C) is past the Due Date (Col. B).

I know how to use conditional formatting, but only in the basic sense. Please help - thank you!

(Col. A) Red = If the Ship Date (Col. C) is past the Due Date (Col. B)
Yellow = Ship Date is 1-13 days before the Due Date
Green = Ship Date is 14+ days before the Due Date

Hi DILIPandey -

I don't understand what you're trying to show me. All I see is that in col. D2, you had put the formula =C2-B2....this is just a simple subtraction formula, but how does that help my issue? Or am I looking at your resolution incorrectly?