date function, for a tracker

I'm trying to keep tabs on my guys first aid certs via an excel spreadsheet. I've entered there name in column A, and the expiry date in column B.

How do i then get column C to show how many days or months are remaining?
Ideally i would have the guys with 3months or more left in green 1-2months amber and <1month in red.

Any help would be appreciated as i've ran out of ideas.

Thank you for your time.

Hi,

You can set this up in Format > Conditional formatting and set something like this

Here's a link on CF

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

Glad it helped - thanks for the feedback