Download the IDE
The Arduino IDE allows you to program any Arduino board. It can be downloaded here. It is also possible to use the Arduino Web Editor, which you can find here.
About the Arduino Due
While most Arduinos have a logic level of 5V, the Due operates at 3.3V. While most digital pins can tolerate 5V, note that the maximum voltage for analog inputs should be 3.3V to ensure an accurate read. If using the Arduino IDE, it is also necessary to download the board package that supports the Due. A pop up should appear prompting this when you first plug the Due into your computer. After downloading this package, from Tools, select the port that the Arduino is plugged in to and set the board to Arduino Due (Programming Port). Now, you can begin to code.
Documentation
The Arduino language is a C++ hybrid. The documentation can be found here.
Serial Monitor
The serial monitor is a debugging tool that allows you to print output to your computer screen. On the IDE, it is the rightmost button on the toolbar and looks like a magnifying glass. To print to the serial monitor add Serial.begin(9600); to setup and Serial.println(“some text”); whereever you want your print statements to be. When viewing the serial monitor, make sure that the baudrate is the same as the one initialized in setup, 9600.