Anyone who's started learning about microcontrollers and code could tell you that a good place to start is by looking at the most basic example sketches provided. As often times their simplicity can teach you a lot more than you think. The Arduino blink sketch is deceptively short yet teaches you so much about how the Arduino IDE and Arduino boards work.
Watch this video and follow the instructions on Instructables.com to build this project yourself.
Full tutorial on Instructables.com