Answer 1

chelangat tom
For starters, you should get an Arduino (compatible) board and write a programm in C++ to light up 3 LEDs (red, yellow, green) just like a traffic light would do.
Once you have that, you can use relays to control heavier loads like the powerful lights of real traffic lights.
To make things more professional, you can switch from an Arduino to an Attiny, for example.
Hope this helps :)