How to set-up end stops in Arduino/Grbl

Hi all, I have installed my end stops. What do I have to do to set them up to work properly? I have the black wire connected to the black pin and the green wire connected to the white pin(to match the + & - of X and Y axis on the CNC Shield. I have manual control of the axis’s in both + and - directions in X & Y.

Arduino Uno
Protoneer CNC Shield v3
Markerbot switches

Thanks for the help

The second entry Google found for me gives the answer. Is that so hard? Configuring GRBL


Here is a link to the new site if anyone needs it. Easy as pie and no unnecessary comments...