how to change the break light on 2007 Cadillac CTS

This is the first time that my break light has gone out.

How do i due it from the trunk and what size bulb do I use

Asked by for the 2007 Cadillac CTS
Stop by your local Napa Auto Parts and have them show you, The bulb number is 3157, But let them look it up for you to make sure
1 more answer
you got to pull the carpet back in the trunk, then take the screws out of break light assembly, then pull the whole assembly out of car.