I added doctors (yellow) so when they come in contact with sick turtles (red), they become healthy turtles (blue). I also added mosquitoes (grey). If the mosquito comes in contact with a sick turtle, the mosquito turns white indicating that it is now carrying the infection. When the infected mosquito (white) comes in contact with a healthy turtle (blue), that turtle becomes sick (red).
The difficulty I have is when I know what I want to accomplish and I then get stuck on something. This obviously causes frustration. I'd like to better understand the codes. I find that I can look through tabs and figure out what I need to do by duplicating something that's already been set up. But I would like to be able to figure it out on my own without needing to sneak a peak in the other tabs. I guess this just takes practice.