Excel formula for logbook

I have my logbook duplicated in Excel, but now that I've added my instrument
rating, it might be nice to have Excel keep track of my currency on
approaches. Maybe flag a cell as red or green depending upon my status...

Unfortunately I'm just barely competent with the program and don't have a
clue about how to go about this. The best I can do is create a formula that
returns a date 6 month previous.
Where to go from there and how to tie the date column to the approaches
column is beyond me.

Any one of you folks have this formula setup already, or have a few hints
that could point me in the right direction?
--
Jeff 'The Wizard of Draws' Bucchino
Cartoons with a Touch of Magic�
www.wizardofdraws.com
www.cartoonclipart.com