It's really clear from the moment you are hired. You work with your supervisor on current job requirements/goals, and then talk about where you want to be. You get trackable goals that you can hit and when you hit them/exceed them you get your promotion.
Help answer questions real people are asking about your company. Your answers will be 100% anonymous.
The person asking the question will be notified of your answer, and it will be posted publicly. Your identity will be kept private