This site is designed to teach concepts of robotics in a step by step manner, starting with the easier to understand topics and going to very challenging topics.
If you are new to the site or to programming, start with the Getting Started category of topics. From there, continue going through the topics until you find something that you consider a challenge or a new concept.
Each topic you learn about is a building block to creating more advanced and interesting programs. You are encouraged to try new and different things based on these building blocks.