Traffic Light with user defined timeframes.

Question

I am trying to create a traffic light that collects user inputs to run the lights. I want to use graphics methods to draw the traffic light. The user will enter the number of seconds each light will stay lit. I have a start button to start the light and a stop button to stop the light. The lights will start one after the other and continue to run until the stop button is clicked. I have no clue at where I should begin.