how can I get a cell to change color by date to indicate expiery t

[nathan the excel idiot]

I'm trying to get the cell color to change from green to yellow to red as a
date entered in the cell gets closer to that date plus 12 months or 36 months.

ie some task was completed on 1 Jan 08 and will last for 24 months so I want
the cell to read green if the date is still good turn yellow a month or 2
before it expires and turn red and clear the date if expired. So if the cell
is empty it should show red. But I want to be able to update the date the
task was completed ie it was completed again on the 15 Dec 10 before it
expired so I want the countdown to expiration to restart for another 24 month
period.

now along with this i want to use the dates as a percent, say all the dates
in a row are task that have been completed so everything is 100% done, and as
they expire start reading 90%, 70% ect until the task is completed again
raising the percent.

I am really lost and have no clue what I am doing and I'm not very good with
excel and find even the help menu confusing plus I can barely do a simple
sum, can anyone help me?

 

[Gary''s Student]

Use Condtional formatting:

http://www.contextures.com/xlCondFormat01.html