Hi,

If you are using Excel 2003 or earlier you can use Format, Conditional
Formatting but you are limited to three conditions.  To get around that you
would need to use VBA.

In Excel 2007 the Conditional Formatting is limited only by memory so you
can handle as many colors as you want.

In 2003 you would select the cells you want formatted and choose Format,
Conditional Formatting, in the second box you would choose Equal to, in the
third box type Red, then click Format, and on the Patterns tab pick red.  
Click OK once and then Add.  Proceed as above.