Colours are created using a 3 number variable, COLORNAME = (red, green, blue), where each colour value is between 0 and 255.
BLACK = (0, 0, 0) WHITE = (255, 255, 255) RED = (227, 27, 27) GREEN = (0, 255, 0) BLUE = (0, 0, 255)
Colours can also be written using hexadecimal numbers. This is handy as frequently colour charts will give you a colour in that form.
For instance, the colour PINK might be
#ff99cc. To use that as a Python colour variable, you would write it as:
PINK = (0xFF, 0x99, 0xCC)
To get a colour at a given pixel
pixel_colour = window.get_at(( x , y ))
A good online resource for picking colours is https://htmlcolorcodes.com