Just because Arduino is open-source and available everywhere, doesn't mean it's intuitively understood. If you're new to the world of Arduino boards and projects, get familiar with what Arduino is and why you'd want to use it. Also introduce yourself to the Arduino Software (IDE) and find out what the heck libraries are. The Getting Started page is a good place to start, but if you want to dive in, we recommend the Getting Started with Arduino, 3rd. edition book. Using practical lessons will teach you enough to get going or at least give you the confidence that you can take just about any input and control an output.