Using esenthel v1

Hi , i have done this long time ago on another
engine so i cant even compare it with esenthel engine..

I want to place grass on the terrain by looking
through the textures pixels color , if i find some pixels close to green
I then want to add grass at that position of the texture ontop of the terrain and modify the grass color to math the green pixel ..

So in other words i need to scan through an area or distance ,retrieve the material , retrieve the image (i tried this wasnt sure if i did it correct but seemed to work) now
The next step is where i am having difficulties
Next i need to go through the pixel colors of the image and find a pixel that is green (or any color i need) after i found it
I need to calculate the position of the pixel in world so that i may place a grass object on its location onto the terrain ..

I am lost at how i would do that , any advice or example would be highly appreciated please.

I know there could be simpler methods but i really want to come closer to this sort of thing ..

Thank you.