Stereo Install in 2000 Pontiac Grand Am

First of all you will need  the right parts. Among them a wire harness an antenna adapter and an installation kit for a Pontiac, but only if you're installing an aftermarket radio.

Metra Kit                            99-3320

I use metra products,   but there are  other companies out there.  instructions to how to remove the radio will come with the installation kit. But as you said " it looks like if just pops off " if I remember correctly, remove the plastic ring around the ignition switch,  the panel will pop off,  make sure  to  remove cigarrete lighter and ashtray. I dod remember being any screws other then the 3 ( 7mm ) holding the radio. But then again the Metra kit  will come with instructions on how to dissemble  the  dash  panel.  Good luck and test all your wires. Also if the car has factory steering wheel   it will stop working  unless you use an adapter which your  buy  from a retail store in your area.  but  the radio  will have to  have a remote, or otherwise do  not worry about it.

Luis