Hello,
Please format your code as per:
https://discourse.processing.org/faq#format-your-code
This is the same code as you provided here:
https://discourse.processing.org/t/help-with-error-in-robot-class-and-createscreencapture-method/30396/1
I provided you with a link in the topic above to a working example that you can modify to get a PImage of the screen.
Please correct your code and then take the next step.
Once you get a PImage you can use get():
https://processing.org/reference/get_.html
See tutorial:
https://processing.org/tutorials/pixels/ Intro To Image Processing section has a good example to work with!
https://processing.org/tutorials/color/
:)