"Conditional Formatting" on dates

I have a training matrix which has the names of the trainees for the columns.
The rows are used for the subjects.
Some of the training competencies are due for refreshers annually, while some are due for refreshers 3 yearly.
The entries in the colums for each participant against the competencies are recorded on the day of the training.
I want to set up "Conditionally Formatting" as an indicator on who is due for refresher training (30 days - yellow) and who have expired (red).
Ideally, I do not want to set additonal rows or colums for expiry dates, I want to only keep the dates of issue.

Excel 2003