I just got my raspberry pi yesterday and have gone through all the setup and update steps required to enable the camera extension (which took me like 6 hrs; yes, I am a newbie). 
I need to create a focus point on the camera's output and use the arrow keys to move this point around the screen. 
My question is how to access the pixel addresses in order to achieve this (if that is even how to do it). Please can one of you gurus out there point me in the right direction.
You do realise that the Pi Camera board has a fixed focus at 1m to infinity ?
& If you want focus <1m you're gonna have to manually twist the lens, after removing the glue that fixates it in the housing.
A focus point on the raspberry pi camera