I am trying to set up a document review alert system
Column A = Document ref No.
Column B = Document Title
Column C = Document review date (input by user)

I am using the typical Red, Amber, Green system

Therefo
if today is more than 60 days prior to review date then no formatting
if today is between 60 to 31 days prior to the review date then the cell
will be green
if today is between 30 - 1 day prior to the review date then the cell will
be amber
if today is either 0 or past the review date then the cell will be red

How do I achieve this? (please specify whether it's a formula or an array as
I'm easily confused). Ideally this would auto calculate each time the
spreadsheet is opened.

Thanking you all in anticipation of your assistance

Terry