I need some one to help me...

I have a 1992 Toyota Runner

Inside I have:
CD player
DVD player
7.2 inch Screen
1200 watt audiobahn amp
2 15 inch subs

I plan on having:
under car neon kit
neons inside
2- 5.5 inch screens
crossovers etc...

My ? is im running a normal battery and Normal alternator i just ordered a 200 amp alternator ... When i put this on do i need to do anything else? All i do is mount it in and plug it up right, i just dont unerstand the concept of where the extra amps go?
I know i need more power because when my bass hits my light dim and i know im gonna need some more when i had my other stuff ... some one please help and it would be great if i had some one to e-mail so i could comunicate with im kinda of a newbie wanting to learn and trying to do things right!
Thanks
Ronnie