Conditional Formatting – Icon Sets

Hi,

I am sure this is easy to do but I have searched online and I can not find a tutorial

I have spotted the icon set feature in excel 2007 and would like to use in on the attached spreadsheet.

Can anyone help with how I set it up. I only require two traffic lights based on actual vs budget (red if actual is worse and green if actual is better than budget).

I want to use the icon set rather than shade the cells (its a bit more modern)

Paul