Hole in firewall

I have a 2006 focus 3 door and i want to put a system in it and i want to wire it right and i can't find the hole in the firewall that i can put the amp wire through, if anyone can help me that would be great thank you

I did'nt have to make a hole for mine. Ok so you have to lift up your air intake so it will be easier to see the entrance I'm talking about, then you have to unclip the fusebox thats against the firewall after you've done all this you look down and theirs going to be a oval shaped black plastic thing so once you've spotted it go inside your car and lift up the carpet thats against the firewall and after you lifted it up there you will see the screw for the plastic thing or the nut might be on the other side I don't remember

hope this helps