need help with brake lights

I'm having a hard time getting into where I can replace my brake lights. I'm trying to unscrew the plastice screws in my trunk, but they never come all the way out. I've got a 1998 and I'm not sure if I'm trying to wrong path to get in there. Can anyone help a (very limited) car person? Thanks.

The probelm may be that they are not "screws", they may look like phillips head screws, but they are pins..give a light pull on the carpet, they should pop out. careful not to break the pins though, however if you do, its not that big of a deal.