i found many stuff about the installation off the voria repo on Ubuntu but i dont know exactl what to do with this whole infos.(Linux starter)

My Laptop is an Samsung RV520 with an Geforce GT520m graphic.
I first line i need the backlight control. I have a fresh installation of Ubuntu 12.04.
My question can somebody post me a exact howto what i must do
in example
1. add repo
2. ....
3.....
that would be very great!
thanks a lot