You are now ready to start the Arduino Software, so whatever platform you are using, open the Arduino folder and open the Arduino application contained within it.
This will start the Arduino IDE, but before you can get programming, you have to tell the Arduino software which type of Arduino board you are using and also select the port it is connecting to.
To tell the Arduino IDE which type of board you are using. From the 'Tools' menu, select Board and then 'Arduino Uno' or 'Leonardo' as appropriate.
Also on the 'Tools' menu, you will find the 'Serial Port' option. Select this option.
If you are using Windows, there will probably only be one option here and it will either say COM3 or COM4. Even though there is only one option, you will still need to select it.
If you are using a Mac or Linux, there will be
more options there, but it will usually be the top option in the
list, as this will be the device most recently plugged in. This is
useful, as the name of the port may not look like it has anything to
do with Arduino. It will probably be called something like /dev/tty.usbmodemXXXX or /dev/ttyUSBn
In the next lesson, you will start by programming your Arduino board to make its built-in LED blink.