Brand new lighting for my grow.

Hello.
 
I'm pretty new to growing, and all this ballast stuff worries me.
 
I'm planning to purchase a iPower digital ballast because the normal ANSIs scare the living hell out of me.
 
 
I've noticed there is an "In" port, for where you plug it in, then there is another cable that comes out with a weird looking socket.
 
What connects there? The Hood?
 
I'm going to be using 400W Metal Halide and 400W HPS.
 
If that is the hood connection, link me to a good, low cost hood?
 
If its NOT the hood, link me to what I need?
 
Thanks!

 

Really need this answered.