Help needed for a novice!

I have recently brought my first Golf GTI 1.8 T mark IV registered in 2000.
I am trying to wire up an amp to my battery and need to run a power wire through my firewall (so i have been told, as i cant see any other way of doing it).
I understand that there are unused holes in the firewall and have looked but with no luck. I have taken some of the carpet back and the numerous layers of insulation etc but have avoided removing it all as i feel the pile would just mount up of interiour parts etc...
Can anyone help me in telling me where i will find a hole to save me removing everything and the correct way to run the wire through my car.
Thanks for any help, i need it!!!

hey,
I drive a 96 VR6 and I hooked up my system. I know what your talkin bout. Mine was superhard to find. i found a tiny hole on my cowl at the top of the engine. from there it went on the inside of the cowl and found another hole that went inside the car through some padding (on passenger side). i had to pull the passenger side vent off and glove box but it was well worth it to find a nice hiding spot.
good luck on makin it nice and clean and unoticable.