Sub And Amp For 99 Lexus Rx300, Please Help.

[allvuong]

ive been researching this forum and the audio video forums for hours and havent come across anything useful. i have the 99 rx300, and my front deck says premium audio system. i've heard people say that the sub its beneath the passenger seat, but no one says how to get to it. from the front, there is a plastic piece covering it, how does it come off, and from the back, there is black plastic. i've also seen people say that the amplifier is behind and under the rear seats, but people dont say weather left or right seats, ive looked and seen nothing. all i want to do is to install an amp and a subwoofer , but i need a way to get to the signal for input for the amp. am i missing, because everytime i try to access something throughout the car, something breaks. btw, can someone give me instructions on how to remove the door panel, i tried removing the speaker grille, stupid design, clips broke. all i need is signal input to the amp, can someone help?