conditional formatting and timelines

Hello,
I am creating a timeline with several tasks and there is a review process
for each task. Each review needs to be completed within a certain timeframe
that corresponds to the due date (in other words, review 1 must be completed
14 days in advance, review 2 needs to be completed 12 days in advance, etc.).

However, if the due date is getting closer (within X days), I want the cell
to be highligted yellow. If it is within X days, I want the cell to be
highlighted red, and if the review is completed on time, it will be green.

The purpose is to show where the hold ups in the review process occur and to
give an up-to-date status on where we are in the review process.

Does this make any sense? Can anyone help?? THANK YOU!!

Select the cells you want - go to "FORMAT" and select "CONDITIONAL FORMATING" and start answering the questions, for the various conditions you want.