take the center fascia off and you need two keys i believe to take out the head unit if its anything like an aftermarket dash kit. if not just unscrew all the screws holding it in the dash and buy a dash kit for the car and install it, very basic and easy, not sure you need to do this though you should just be able to take it out with a key. if you cant find a key to take it out, on each side of the dashkit there is a metal tab bent in that holds the head unit in, there should be enough room for you to stick your hand in there and bend it out on each side. then pull the headunit out

 

Open up the ash try, put your fingers underneath the whole radio cover area and pull. There are 3 clips on each side. Just pull with constant pressure and it will pop off.

 

dunno about the 06 HU but i know with my 03 gt HU i just had to pop open the ash try, pull out the fascia, or whatever they call it, then there were 4 screws holding the HU on.

very simple stuf.