Open the Arduino software and paste the Arduino code (the text in the box near the bottom of the post) into a new sketch. Click Sketch > Verify / Compile to make sure the code is properly in there.

pinMode' is a built-in Arduino function that sets how a given I/O pin on the Arduino behaves - either input or output. In this case, we're telling the Arduino to use pin LED_BUILTIN (13) as an ...