Who can explain how to work with holes for wires (if I can put it that way) in circuits, devices?

Question

Circuit design

1) In the first photo, the device itself, the network controller, in the second, a small diagram of how to connect several devices, as I understand it, they are needed for communication between them, information is transmitted between them? Or something different?
2) How to write a program for such a device?

Answer 1

"they are needed for communication between them" - who are THEY?
The program is written like this: taken and written. More specifically with such introductory not to say.