See
for some sample color picker apps.
I read the starter tutorial you linked, and I assume you have an aia and want to fill in
- the part where you can get a better name for the RGB color value of the chosen picture pixel. That's easily done in a dozen blocks and a given color name/code file.
- some kind of interactive user test where he is pointed to a random spot on a picture and asked to recreate that color on one of the sample color pickers in the above color FAQ?